You can put this solution on YOUR website! if the angles are supplementary, then their sum is 180 degrees.
you get 5x - 2y + 20 + x = 180
combine like terms to get 6x - 2y + 20 = 180
subtract 20 from both sides of this equation to get 6x - 2y = 160
add 2y to both sides of this equation and subtract 160 from both sides of this equation to get 6x - 160 = 2y
divide both sides of this equation by 2 to get 3x - 80 = y
that should be your solution because that is the value of y in terms of x.
the solution is y = 3x - 80.