a) 2(x+3) = 30

2x + 6 = 30

2x = 30 - 6

2x = 24

x = 24 / 2

x = 12

b) 8 - 2(x+5) = 5

8 - 2x - 10 = 5

8 - 10 - 5 = 2x

- 7 = 2x

x = - 7/2

c) 3(y-1) - 4(y-2) = 6

3y - 3 - 4y + 8 = 6

- y = 6 + 3 - 8

- y = 1

y = - 1

d) 2(5y+1) = 27

10y + 2 = 27

10y = 27 - 2

10y = 25

y = 25 / 10 simplifica por 5

y = 5/2