Question

Find the GCF of each pair of monomials.
1). 20, 45x

Answer 1

The greatest common factor is 5 

Answer 2

20 and 45x

We look for a number that can go into both numbers.

5 into 20 is 4 and 5 into 45x is 9x.

5: 20 45x

4 9x

So no other number can go into 4 and 9x again.

So the GCF of 20 and 45x is 5.

Hope this explains it.