Ok, so I have this expression, and I need some help on it:

15abc - ab + 3ab

I'm guessing that first you go: ab + 3ab (cos ab= 1ab, and 3ab and ab are therefore like terms)

That would then leave me with 15abc - 4ab

That is what I understand so far, but can this expression be simplified further?

If so, how ?

THANKS!