First, find the GCF, or greatest common factor, of the numerator and denominator. If one number ends in 25 and the other ends in 00, then a factor of both is 25:
325/25 = 13
1000/25 = 40
Our new fraction is 13/40, and, seeing as that has a prime number, 13, it cannot be simplified, so that is the final answer.
Hope this helps!
~ArchimedesEleven