Question

1)178-(23-x)=11; 2)21х-7х=510

Answer 1

1) 178 - 23 + x = 11
x = 11 + 23 - 178 = -144
2) 21x - 7x = 510
7x(3-1) = 510
7x = 510 / 2 = 255; x = 255 / 7 = 36 (целых) 1/3 (одна третья)