Question

How to add and subtract algebraic expressions?

Answer 1

For example:
13x + 7y - 2x + 6a
The only like terms in this expression are 13x and -2x. We cannot do anything with the 7y or 6a.
So, we group together the terms we can subtract, and just leave the rest.
(13x - 2x) + 6a + 7y
= 6a + 11x + 7y