Математика 6кл уравнения

1) 40 - 12x = 20 - 11x

-12x + 11x = 20 - 40  

-x = - 20

x = 20

2) 6x + 10 = 5x + 15

6x - 5x = 15 - 10

x = 5

3) 8 - 5n = 10 - 4n

- 5n + 4n = 10 - 8

-n = 2

n = -2

4) 10a + 7 = 9a +  5

10a - 9a = 5 - 7

a = - 2

5) 30 - 15y = 40 - 14y

- 15y + 14y = 40 - 30

-y = 10

y = -10

6) 6x + 5 = 7x + 3

6x - 7x = 3 - 5

-x = -2

x = 2

7) 3(x + 2) = 4x + 1

3x + 6 = 4x +  1

3x - 4x = 1 - 6

-x = -5

x = 5

8) 4(x - 2) = -(3x - 6)

4x - 8  = -3x + 6

4x + 3x = 6 + 8

7x = 14

x = 2