The simplified fraction is 1/3 and the GCF is 75.
To find the GCF, we find the prime factorization of each number:
75 = 3 * 5 * 5
225 = 3 * 3 * 5 * 5
The GCF is 3*5*5 = 75.
Dividing 75 by 75 on the numerator, we get 1; dividing 225 by 75 on the denominator, we get 3.