Select each value of a for which you can solve the system by elimination without multiplying first.

ax−7y=−13
8x−6y=−2

The options are:
−7

−6

−2

8

42

6

−8

7

How do you figure out which order to do two step equations in? like which thing do you subtract/add/multiply/divide first? i understand that you do the opposite of whatever's shown on the opposite side, but when?