Пошаговое объяснение:
1. – 3х = - 21;
x = -21:(-3)
x = 7
2. 20х = -5;
x = -5:20
x = -0,25
3. 8х + 5 = 0;
8x = -5
x = -5:8
x = -0,625
4. 3х – 7 = 2;
3x = 2 + 7
3x = 9
x = 9:3
x = 3
5. 11 – 4х = 2х;
2x+4x = 11
6x = 11
x = 11 : 6
x = 1 5/6
6. 8х – 2 = 7 + 2х;
8x - 2x = 7+2
6x = 9
x = 9 : 6
x = 1,5
7. 3х + (4 – 6х) = 18;
3x + 4 - 6x = 18
-3x + 4 = 18
3x = -18+4
3x = -14
x = -14:3
x = -4 2/3
8. 6х – (2х + 5) = - 4;
6x - 2x - 5 = -4
4x - 5 = -4
4x = -4+5
4x = 1
x = 1:4
x = 0,25
9. 6 – 2(3х – 9) = - 4х;
6 - 6x + 18 = -4x
24 - 6x = -4x
6x - 4x = 24
2x = 24
x = 24 : 2
x = 12
10. 5 (2х +2) – 5х = 13;
10x + 10 - 5x = 13
5x + 10 = 13
5x = 13 - 10
5x = 3
x = 3:5
x = 0,6
11. (х – 9)(х+13) = 0;
x - 9 = 0 или x + 13 = 0
x = 9 x = -13
12. (4х+3)(2х–1) = 0.
4x + 3 = 0 или 2x - 1 = 0
4x = -3 2x = 1
x = -3:4 x = 1:2
x = -0,75 x = 0,5
2)60-40=20(кг)-в 1 корзине
3)22+20=42(кг)-в 1 и 3 корзинах
4)60-42=18(кг)-во 2 корзине