99 deposited $500 into a bank account that earned 7.5% simple interest each year. she earned $225 in interest before closing the account. if no money was deposited into or withdrawn from the account, for how many years was the money in the account? round your answer to the nearest whole year.

1st year...
500 = 100%
5 = 1% 
2.5 = 1/2% or .5%
So, you have to do 5 x 7 to get 35 which is 7% then you have to tack on the 2.5 to get 7.5%

2nd year...
537.5 = 100%
5.375 = 1%
2.6875 = 1/2% or .5%
So now 5.375 x 7 = 37. 625 + 2.6875 (I will round at the end) = 40.3125
So 37.5 + 40.31 (rounding!) = 77.81 in interest so far.

3rd year...
537.5 + 40.31 = 577.81 = 100%
5.77 = 1%
2.89 (was 2.885 but round up) = 1/2% or .5%
so 5.77 x 7 = 40.39 + 2.89 = 43. 28 = 7.5%
577.81 + 43.28 = 621.09

4th year
621.09 = 100%
6.21 = 1%
3.11 (was 3.105, but round up)
6.21 x 7 = 43.47 + 3.11 = 46.58
621.09 + 46.58 = 667.67

5th year...
667.67 = 100%
6.68 (round up) = 1%
3.34 = 1/2% or .5%
6.68 x 7 = 46.76 + 3.34 = 50.1
667.67 + 50.1 = 717.77

So as a fact, I will go over next year, so your answer is 6 whole years.

Hope this helped! Hope I'm not wrong!

Where are the functions?