Jasmine and her sister are saving to buy MP3 players. Jasmine has $50 and plans to save $10 per week. Her sister has $80 and plans to save $7 per week. In how many weeks will Jasmine have more money saved than her sister? Write an inequality to represent this problem

Let J = Jasmine's money

Let s = sister's money

Let w = # weeks

J = 50 + 10w

s = 80 + 7w

We want to know when Jasmine's total is more than her sister's:

50 + 10W > 80 + 7w

subtract 7w from both sides

50 + 3w > 80

subtract 50 from both sides

3w > 30

divide both sides by 3

w > 10

In 10 weeks they will have the same amount of money .. ($150 each).

In 11 weeks Jasmine will have more money than her sister.