(4·x + 20)·(2·x - 8) + 12 = 5·x^2 + (3·x - 2)·(x + 80)
(8·x^2 + 8·x - 160) + 12 = 5·x^2 + (3·x^2 + 238·x - 160)
8·x^2 + 8·x - 148 = 8·x^2 + 238·x - 160
12 = 230·x
x = 12/230 = 6/115 = 0.05217
(4·x + 20)·(2·x - 8) + 12 = 5·x^2 + (3·x - 2)·(x + 80)
(8·x^2 + 8·x - 160) + 12 = 5·x^2 + (3·x^2 + 238·x - 160)
8·x^2 + 8·x - 148 = 8·x^2 + 238·x - 160
12 = 230·x
x = 12/230 = 6/115 = 0.05217