Реши уравнения 15 / (а+2) = 6 / (2 а+7), 12b-7 / (b+4) = 26-4b, 5 / (3c+2) = 8 / (9-2c), 10k+2 / (7k-2) = 5 / (4k+3) + 3k.

1) 15 * (a+2) = 6 * (2a+7)

15a+30=12a+42

15a-12a=42-30

3a = 12

a=4

2) 12b-7 * (b+4) = 26 - 4b

12b-7b-28 = 26-4b

5b+4b=26+28

9b = 54

b = 6

3) 5 * (3c + 2) = 8 * (9 - 2c)

15c+10 = 72-16c

15c+16c = 72-10

31c=62

c=2

4) 10k + 2 * (7k - 2) = 5 * (4k + 3) + 3k

10k + 14k-4=20k+15+3k

24k-4=23k+15

24k-23k=15+4

1k=19

k = 19:1

k=19