Comparing the cost of the car to the deposit, $3,168.00 the amount required to be added to the deposit
$3,168 is the interest
rate = 8%
time = T
principal = 6,600.00
I = ( PRT)/100
T = 100 I/PR
=(100*3168)/(6600*8)
= 6
She should leave the money for six years.