(2x - 7) + (6x + 1) = 18;
2x - 7 + 6x + 1 = 18;
2x + 6x = 18 + 7 - 1;
x(2 + 6) = 24;
8x = 24;
x = 24 : 8;
x = 3.
(2x - 7) + (6x + 1) = 18;
2x - 7 + 6x + 1 = 18;
2x + 6x = 18 + 7 - 1;
x(2 + 6) = 24;
8x = 24;
x = 24 : 8;
x = 3.