Heres the easiest way to figure this out. You deposit $700 dollars into your account, correct? So, the annual interest rate is 4%. Take 700 dollars and multiply that by 4 percent. You get $28. So, EVERY. SINGLE. YEAR. you get 28$. So, multiply 28 by 5. Thats $140. Then, add 140 into 700, and you get 840.
if she spent 6500 at the beginning and it cost 550 per week, 900-550=350 gain per week... 350 times 19 is 6650 so it takes 19 weeks for them to make a gain
