How do i find thhe greatest common factor?

lets say you needed to find the greates comon factor of 20 and 5, you need to find the closest number they both go into, so 20. or if it was 3 and 10 it would be 30 because it is the closest thing they both go into, i hope i am right i am so sorry if i am wrong.

hello from mrbilldoesmath!

answer:

x - 3

discussion:

x^2 - 9 = (x-3) (x+3)   so

(x^2-9)/ (x + 3) = x-3

you,

mrb

72 is the answer to this problem