Решите уравнения

1) 2 х = 4/3 (х+15)

2) 2/3 (10-х) = - 12

3) - 1/4 (5 х-7) = 6

Ребята вот этим знаком / я обозначила дробь

1) 2 х = 4/3 * (х + 15) 2) 2/3 * (10 - х) = - 12

2 х = 4/3 х + 4/3*15 2/3*10 - 2/3 х = - 12

2 х - 1 1/3 х = 20 20/3 + 12 = 2/3 х

2/3 х = 20 18 2/3 = 2/3 х

х = 20 : 2/3 = 20 * 3/2 х = 56/3 : 2/3 = 56/3 * 3/2

х = 60/2 = 30 х = 168/6 = 28

3) - 1/4 * (5 х - 7) = 6

- 1/4*5 х - 1/4 * (- 7) = 6

- 5/4 х + 7/4 = 6

- 1,25 х = 6 - 1,75

- 1,25 х = 4,25

х = 4,25 : (-1,25)

х = - 3,4

1) 2 х = 4/3 (х+15)

2 х-4/3 х=20

2/3 х=20

х=20:2/3=20*3/2=30

2) 2/3 (10-х) = - 12

-2/3 х=-12-20/3

-2/3 х=-56/3

х=-56/3: (-2/3) = 56/3*3/2=28

3) - 1/4 (5 х-7) = 6

-5/4 х=6-7/4

-5/4 х=17/4

х=17/4: (-5/4) = - 17/4*4/5=-17/5=-3,4