What is 10a+8 factorised

First thing you do, is take out the GCF (greatest common factor)

So, what number goes into both 10 and 8?

Obviously, 1. 2 also goes into 10 and 8. Any higher number that would go into both 10 and 8 and give you a whole number? No. So, the GCF is 2

Divide 10 and 8 by 2, and set that in a set of parenthesis with the GCF outide

2 (5a+4)

That cannot be factored any further, so that is the answer

2 (5a+8) is your anwser