а) 8(3-3b) + 5(3b+5) = 7

24 - 24b + 15b + 25 = 7

-9b + 49 = 7

-9b = 7 - 49

-9b = -42

b = -42 / -9

b = 4.67

б) -6(3t+4) + 4(2t-2) = 7

-18t - 24 + 8t - 8 = 7

-10t - 32 = 7

-10t = 7 + 32

-10t = 39

t = 39 / -10

t = -3.9