Объяснение:

1) 2x + 9 = 15 - x

2x + x = 15 - 9

3x = 6

x = 6 ÷ 3 = 2

2) 17 - 0.3x = 23 + 1.7x

17 = 0.3x + 1.7x + 23

17 = 2x + 23

0 = 2x + 23 - 17

2x + 6 = 0

2x = -6

x = -6 ÷ 2 = -3

3) y - ½y = 0

½y = 0

y ÷ 2 × 1 = 0

y ÷ 2 = 0

y = 0 × 2

y = 0

4) 14 - x = 19 - 11x

11x - x = 19 - 14

10x = 5

x = 5 ÷ 10= 0.5

5) 0.8x + 14 = 2 - 1.6x

0.8x + 1.6x + 14 - 2 = 0

2.4x + 12 = 0

2.4x = -12

x = -12 ÷ 2.4

x = -5

6) x - 4x = 0

x - 0 = 4x

x = 4x

x = 0

7) 0.5x + 11 = 4 - 3x

0.5x + 3x = 4 - 11

3.5x = -7

x = -7 ÷ 3.5

x = -2

8) 15 - x = ⅓x - 1

15 + 1 - x = ⅓x

16 - x = ⅓x

4/3x = 16

x = 16 ÷ 3 × 4 = 64 ÷ 3 = 21 ⅓