(7x) / (7x + 3) = (20x - 4) / ( 20x - 4 + 2x + 2)
(7x) / ( 7x + 3) = (20x - 4) / ( 22x - 2) cross-multiply
(7x) ( 22x - 2) = (7x + 3) (20x - 4)
154x^2 - 14x = 140x + 60x - 28x - 12 rearrange as
14x^2 - 46x + 12 = 0 divide through by 2
7x^2 - 23x + 6 = 0
(7x - 2) ( x - 3) = 0
7x - 2 = 0 x - 3 = 0
7x = 2 x = 3
x = 2/7