Question

what is -6a + a + 28a

Answer 1

$-6a+a+28a=-6a+29a=23a$

Hope this helps.

Answer 2

These are all like terms, meaning that they involve the same literal expression (in this case, "a").

So, we can factor a out of all the terms, and we have

$-6a+a+28a=a(-6+1+28) = 23a$