Answer:
5
Explanation:
5x+15
So let's take them one after the other
5x=1,5,x
15=1,3,5,15
Since 5 is common to the two,So the greatest common factor will be 5
But we can solve further in case we are asked to factorise
5x+15
5(x+3)
So the answer for factorisation is 5(x+3)