Question

what is 4p+3q=36

9p+6q=78 ?

Answer 1

4p+3q=36 (1)

9p+6q=78 (2)
You want to eliminate either the p's or q's to solve for one. Eliminating the q's is easier because you only have to change one equation. Multiplying (1) by -2...
-8p-6q=-72 (3)
9p+6q=78 (2)
Add the equations together.
p=6
Now substitute p=6 in either equation 1 or 2 to figure out what q equals.