What is (3a-b) + 2a equal to?

We add like terms

so remembe that we can add the numbers in front of the placeholders

exg

3a+2a=5a becuase 3+2=5

we cannot add a+b

so

remember the associative property which is a + (b+c) = (a+b) + c

therefor we can move the parenthasees

also remember the commutativer property which is a+b=b+a so we can change

(3a-b) + 2a to (3a+2a) - b = (5a) - b=5a-b