Answer:GCF=17
To find the greatest common factor, or GCF, of the numbers, we first need to list the prime factors of both 85 and 51
52=3*17
85=5*17
17 is the sole common factor that these two numbers have in common, therefore 17 is the GCF.
To simplify the ratio, simply divide both numbers by 17.
85:51 becomes 5:3
