2 years = 24 months.
96 per month x 24 months = 2,304 total amount paid back.
2304 - 2000 = 304 amount of interest.
304 / 2000 = 0.152
0.152 x 100 = 15.2%
This can be rounded to the closest percent, which would be 15% so she is correct.
Divide all three sections height times width times times length and you get your answer.
Small (x)
9(x) + 9(x) - 1 = 30
2 x 9(x) - 1 = 30
2 x 9(x) = 30 + 1
2 x 9(x) = 30
simplify
9x = 31/2
x = 1/2 x log (3) (31/2)
or
x ≈ 1.24741
I hope this helps ( there is no negatives )