## WhiteRabbit 3 years ago You can buy DVDs at a local store fro \$15.49 each. You can buy them at an online sore for \$13.99 each plus \$6 for shipping. How many DVDs can you buy for the same amount at the two stores?

1. tjones89

for this problem you need to create two equations; one that represents the amount of money it would cost to buy a certain amount of movies from the store, and another that shows the money it costs to buy a certain amount of movies online.

2. WhiteRabbit

d = 15.49 and o = 13.99 + 6?

3. tjones89

what you need in those equations is a variable to represent the number of movies

4. WhiteRabbit

m???

5. tjones89

because if I buy 2 movies from the store it will be 2 * \$15.49

6. tjones89

so lets let x = the number of movies I want to buy and y is the amount of money it costs

7. tjones89

if I buy from the store I multiply the number of movies I want to buy times the price of each movie right?

8. WhiteRabbit

why not m and c?

9. tjones89

that works too. m for movies and c for cash?

10. WhiteRabbit

uhhuh ^^

11. tjones89

so the way we can represent the price of movies at the local store is with 15.49m = c

12. tjones89

that make sense?

13. WhiteRabbit

*nods*

14. tjones89

now we can make another equation that shows the price of buying movies online. Can you make that one?

15. WhiteRabbit

i can one sec

16. WhiteRabbit

13.99m + 6 = c

17. tjones89

good

18. WhiteRabbit

^^

19. tjones89

so now the problem asks us how many movies we can buy with the same amount of money at the two stores or for what value of m will both of our equations result in the same number c

20. WhiteRabbit

hmm can we combine them?

21. tjones89

and since 13.99m + 6 = c and 15.49m = c we can set these equations equal to each other because we're assuming c is the same number in both

22. tjones89

its like saying 2+2 = 4 and 1 +3 =4 so we can say that 1 + 3 = 2 + 2

23. WhiteRabbit

29.48m + 6 = c?

24. WhiteRabbit

oh ota, so 15.49m = 13.99m + 6

25. tjones89

yep

26. WhiteRabbit

^^

27. tjones89

can you solve from here?

28. WhiteRabbit

i think so

29. tjones89

let me know what you get

30. WhiteRabbit

m = 4

31. tjones89

yep

32. WhiteRabbit

61.96 = c

33. tjones89

the question didnt ask for that, but yeah good job!

34. WhiteRabbit

it bothers me if i don't solve for all variables ... sorry