Question

What’s equivalent to (18x + 9k) +(2x + 6k)

Answer 1

18x + 9k + 2x + 6k.....combine like terms
20x + 15k or 5(4x + 3k)

Answer 2

Combine like terms.

18x + 2x = 20x

9k + 6k = 15k

20x + 15k is your answer

Note that you cannot combine 15k and 20x, because they have different variables

hope this helps