3x + y = 18
2x - y = 12
we must make both equations have only one variable
we first add the equations top to bottom, and get
5x = 30
we then divide by 5, and get x = 6
now we sub 6 in for x, and solve for y
3x + y = 18 y = 18 - 3x
y = 18 -18
y = 0
the first number is 6, the second number is 0