math
posted by teeka .
how long will it take to earn $525 in interest if $3500 is invested at 6% annual interest rate ?

Pt = Po + r*t*Po.
Pt = Po + I = 3500 + 525 = 4025.
Pt = 3500 + 0.06t * 3500 = 4025,
3500 + 0.06t * 3500 = 4025,
0.06t * 3500 = 4025  3500,
0.06t * 3500 = 525,
210t = 525,
t = 525 / 210 = 2.5 years. 
Pt = Po + r*t*Po.
Pt = Po + I = 3500 + 525 = 4025.
Pt = 3500 + 0.06t*3500 = 4025.
3500 + 0.06t * 3500 = 4025,
0.06t * 3500 = 4025  3500,
0.06t * 3500 = 525,
210t = 525,
t = 525 / 210 = 2.5 years.