We'll have to assume that interest is charged annually.
interest = i = p*r*t, where p is the initial amount ($25000), r is the annual interest rate as a decimal fraction, and t is the length of time, in years.
Then $2625 = $25000*0.035*t. Solve for t:
$2625
------------ = 0.035t = 0.105. Dividing both sides by 0.035, we get
$25000
t = 3 years (answer)
