+129840 3x - y = 18
4x + 2y = 24
Add y to both sides of the first equation and subtract 18 from both sides
3x - 18 = y
Substitute this into the second equation for y
4x + 2(3x - 18) = 24 simplify
4x + 6x - 36 = 24 add 36 to both sides and simplify the left side
10x = 60 divide both sides by 10
x = 6
And using 3x - 18 = y → 3(6) - 18 = 18 - 18 = 0 = y
