реши уравнения 15: (8-x) + 9=12, (8 * x-140) : 6=30, x; 9+8=12,5 * (15-x) - 7=28

1) 15 : (8 - x) + 9 = 12;

15 : (8 - x) = 12 - 9;

8 - х = 15 : (12 - 9);

8 - х = 5;

х = 8 - 5 = 3;

2) (8 * x - 140) : 6 = 30;

8 * x - 140 = 30 * 6;

8 * х = 180 + 140;

х = 320 : 8 = 40;

3) x : 9 + 8 = 12;

х: 9 = 12 - 8;

х: 9 = 4;

х = 4 * 9 = 36;

4) 5 * (15 - x) - 7 = 28;

5 * (15 - x) = 28 + 7;

15 - x = 35/5;

х = 15 - 7 = 8.