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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?

  • 2 years ago
  • 2 years ago

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

    • 2 years ago
  2. sws._. Group Title
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    yeah

    • 2 years 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

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

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

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

    • 2 years ago
  7. sws._. Group Title
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    yeah

    • 2 years ago
  8. geoffb Group Title
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    Use C and M for your variables.

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

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

    • 2 years ago
  11. sws._. Group Title
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    4m ?

    • 2 years ago
  12. geoffb Group Title
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    What is 4M?

    • 2 years ago
  13. sws._. Group Title
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    4 times michaels age

    • 2 years ago
  14. sws._. Group Title
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    4 * M

    • 2 years 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

    • 2 years 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?"

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

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

    • 2 years ago
  19. geoffb Group Title
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    Does that make sense?

    • 2 years 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.

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

    • 2 years ago
  22. sws._. Group Title
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    no wait..

    • 2 years ago
  23. sws._. Group Title
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    does 9 go outside?

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

    • 2 years 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.

    • 2 years ago
  26. sws._. Group Title
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    ohhh

    • 2 years ago
  27. geoffb Group Title
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    Yes, right! The 9 goes outside.

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

    • 2 years ago
  29. geoffb Group Title
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    Yes! But what is x?

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

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

    • 2 years 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?

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

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

    • 2 years 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.

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

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

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

    • 2 years ago
  39. geoffb Group Title
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    And you need your full formula.

    • 2 years ago
  40. geoffb Group Title
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    But you're doing great.

    • 2 years 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.

    • 2 years ago
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