We need I = prt, where p = principle, I = interest, r = interest rate and t = time (in years).
I = prt
14 = 100r(1)
We now solve for r.
14 = 100r
Divide both sides by 100 to isolate r.
14/100 = 100r/100
0.14 = r
Now change 0.14 to a percent multiplying by 100.
100(0.14) = r
14 = r
The interest rate is 14%.