We solve for t before substituting, because it's
easier than substituting first:







Divide both sides by 



A = final amount = $18221.60
P = beginning amount =$17000
n = number of compoundings per year = 4 (since it's quarterly)
r = 7% as a decimal, 0.07
t = number of years = ???

Plug in:





Rounds to 1 year.

Edwin