So you want to isolate one of the variables in one of the equations. Using the first equation, we can make 3x+y=2 y=2-3x.
Then plug y=2-3x into the second equation:
4x+(2-3x)=20
Then solve.
x+2=20
x=18
Finally, plug the x value back into any of the two equations to find y. This is essential to get full credit!
4(18)+y=20
72+y=20
y= -52
x=18
y= -52
