...your sister spent her WHOLE allowance? im not sure if u wrote this problem correctly.
lets just pretend your sister IS spending 7 dollars each week. you're saving while she is spending (smart).
80 + 6w = 145 - 7w
...subtract 80
6w = 65 - 7w
...ad 7w
13w = 65
...divide 13
w = 5
it will take only 5 weeks for you two to have the same amount of money.
