Answer:
81 ............................
2x^2-7x-18x+63
2x^2-25x+63
Assuming the price of the pool does not change, then
Additional interest required is 4500-3750=750
using
I=Pit, we set up equation
750=3750*0.055*t
Solve for t
t=750/(3750*0.055)=3.64 years.
So will need to wait 3.64 years, or rounded up to 4 years.