Both are primes, so their gcf is 1.
But..
If you're using the stupid SwitchedOn Online Integrated Math course, they say it's 3.
I couldn't tell you why, but I put 1, knowing they're both prime (and 1 goes into both), and they said it was wrong.
So. Yay for idiot mathing :)
The GCF of 3 and 5 is 1. To help you understand this, here are the factors of each.
3 5
1x3 1x5
1 is the greatest factor that is common out of both of them.
GCF of 5 and 3 is 1.
The GCF is 1.
75 = 3 * 5 * 5 and 285 = 3 * 5 * 19 they have in common ( 3 * 5) So the GCF is 15.
The GCF is 1.
3 = 1 x 3 5 = 1 x 5 7 = 1 x 7 GCF = 1
The GCF is 1.
The GCF is 1.
The GCF is 1.
The GCF is 1.
GCF (125, 80, 225) = 5
The systematic way to get the answer is: 90 = 2*3*3*5 210 = 2*3*5*7 So gcf is 2*3*5 = 30
The GCF is 1.