Question

add the like terms: -3ab+-10a+-8a

Answer 1

-10a and -8a are like terms, but -3ab is not equivalent.  With the two a terms, we have:

-10a-8a

a(-10-8)

-18a

We then add in the other term (-3ab) for a final result of -3ab+-18a.  This can be factored alternatively as -3a(b+6).

Answer 2

Check below! :D Answer is -3ab-18a.