Ответ:

e) 5x + 21 = 3x + 35;

5x-3x = 35 - 21;

2x = 14;

x = 14 / 2;

x = 7;

f) 17 - 3x + 7x = 31 - 2x + 10;

-3x + 7x + 2x = 31 + 10 - 17;

6x = 24;

x = 24 / 6;

x = 4;

g) 2x - 12 = 2(10 - 7x);

2x - 12 = 20 - 14x;

2x + 14x = 20 + 12;

16x = 32;

x = 32 / 16;

x = 2;

h) 5x - 12 - 2(x - 1) = 3(5 - 2x) + 4x;

5x - 12 - 2x + 2 = 15 - 6x + 4x;

5x - 2x + 6x - 4x = 15 + 12 - 2;

5x = 25;

x = 25 / 5;

x = 5