A = P ( 1+r )^ t
A = the future value including interest
P = the principal = $15,000
r = the annual interest rate = 6% = 0.06
t = the number of years = 5 years
So
A = 15,000(1 + 0.06)^5
A = $20,073.38
Answer
She will have paid $20,073.38 at the end of the five year
