Solving our equation
r = (1/8)((7000/4480) - 1) = 0.0703125
r = 0.0703125
converting r decimal to a percentage
R = 0.0703125 * 100 = 7.0313%/year
The interest rate required to get
a total amount, principal plus interest, of $ 7,000.00
from simple interest on a principal of $ 4,480.00
Hope it helped
over 8 years is 7.0313% per year.