To substitute, solve for one variable and then plug it into the other equation you have. In this problem, y is already solved for on the top equation (y=x+2), so you just stuff it into the second equation.
y = x + 2
3y = 4x - 2
3(x + 2) = 4x - 2
3x + 6 = 4x - 2
-x = -8
x = 8
y = x + 2 = 8 + 2 = 10
solution:
x = 8
y = 10
hope this helps!! :)
