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sws._. Group Title

Christopher is 4 times as old as Michael. Ten years ago, Christopher was 9 times as old as Michael.How old is Christopher now?

  • one year ago
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  1. geoffb Group Title
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    Are you able to turn the sentence into an equation?

    • one year ago
  2. sws._. Group Title
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    yeah

    • one year ago
  3. sws._. Group Title
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    i think that is what im supposed to do, but im having trouble setting it up

    • one year ago
  4. geoffb Group Title
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    Okay, no problem. Do you have a guess as to how you would start?

    • one year ago
  5. sws._. Group Title
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    4x-10 is this one side of the equation?

    • one year ago
  6. geoffb Group Title
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    Can you write an equation for right now? Let's say time = 0 right now.

    • one year ago
  7. sws._. Group Title
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    yeah

    • one year ago
  8. geoffb Group Title
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    Use C and M for your variables.

    • one year ago
  9. sws._. Group Title
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    okay but how would i set it up?

    • one year ago
  10. geoffb Group Title
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    "Christopher is 4 times as old as Michael." Write that algebraically.

    • one year ago
  11. sws._. Group Title
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    4m ?

    • one year ago
  12. geoffb Group Title
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    What is 4M?

    • one year ago
  13. sws._. Group Title
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    4 times michaels age

    • one year ago
  14. sws._. Group Title
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    4 * M

    • one year ago
  15. geoffb Group Title
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    Right. But you need an equals sign and something on the other side. For example, if steak is 10 times heavier than rice, steak = 10 * rice, which as a formula would be S = 10R

    • one year ago
  16. geoffb Group Title
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    So how would you write a formula for "Christopher is 4 times as old as Michael?"

    • one year ago
  17. sws._. Group Title
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    4m=10(4x-9) ? i have no idea ._.

    • one year ago
  18. geoffb Group Title
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    That's okay. Not to worry. It's C = 4M

    • one year ago
  19. geoffb Group Title
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    Does that make sense?

    • one year ago
  20. geoffb Group Title
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    That is a perfectly valid statement for right now. Now, the tougher part, you need to write a formula for 10 years ago.

    • one year ago
  21. sws._. Group Title
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    oh okay i know that 10 has to be outside the parenthesis

    • one year ago
  22. sws._. Group Title
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    no wait..

    • one year ago
  23. sws._. Group Title
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    does 9 go outside?

    • one year ago
  24. sws._. Group Title
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    because it says 9 times as old as Christopher

    • one year ago
  25. geoffb Group Title
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    On the side where parentheses matter, the 10 will actually need to go inside. You need to write an equation for the second statement which uses the variables for their current ages. That might sound complex, but it's as simple as: My current age might be x. I can say that 10 years ago, my age was x - 10. It doesn't matter what x represents; x - 10 is valid no matter what.

    • one year ago
  26. sws._. Group Title
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    ohhh

    • one year ago
  27. geoffb Group Title
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    Yes, right! The 9 goes outside.

    • one year ago
  28. sws._. Group Title
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    okay so it would be 9(x-10) ?

    • one year ago
  29. geoffb Group Title
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    Yes! But what is x?

    • one year ago
  30. sws._. Group Title
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    i mean c. im using x instead of c

    • one year ago
  31. geoffb Group Title
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    Remember, you need an equal sign, and stuff on both sides of it.

    • one year ago
  32. geoffb Group Title
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    Okay, we can use x instead of C. But then what are we using instead of M?

    • one year ago
  33. geoffb Group Title
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    Remember, for now, we are keeping their ages separate.

    • one year ago
  34. sws._. Group Title
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    i guess we can use y or m but i like x instead of c

    • one year ago
  35. geoffb Group Title
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    Sure. Okay, so in the formula I gave before, x = 4y Chris (x) is 4 times older than Michael (y) right now.

    • one year ago
  36. geoffb Group Title
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    So now, we need to do our "10 years ago" formula.

    • one year ago
  37. sws._. Group Title
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    would it be the one i mentioned before?

    • one year ago
  38. geoffb Group Title
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    Yes, but you used x. It should be y.

    • one year ago
  39. geoffb Group Title
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    And you need your full formula.

    • one year ago
  40. geoffb Group Title
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    But you're doing great.

    • one year ago
  41. geoffb Group Title
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    @sws._. Mention me if you feel like continuing. I'd like to help you learn this so you can do your other 11 questions.

    • one year ago
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