Time Dilation Problem

If an astronaut's trip through space takes 25.0 years as measured relative to earth and 1.50 years as measured by timing devices aboard the space vehicle, at what speed was the vehicle traveling relative to earth?
T=t/√(1-v^2/c^2)
T=25.0 years
t=1.50 years
c=3.00x10^8 m/s
v=?
so in this problem we are finding v (velocity) so how would I manipulate the equation? :S

First multiply both sides by denominator (after the /). Then divide both sides by T.
Sqrt(...) = t/T
Square both si