2ab - 3a/b = 15

ab + a/b = 10

Замена:

t = ab

l = a/b

2t - 3l = 15

t + l = 10

(2t - 3l) + (t + l) * 3 = 5t = 15 + 10*3 = 45

5t = 45

t = 9

l = 10 - t = 10 - 9 = 1

ab = 9

a/b = 1 ==> a = b ==> a*a=9 ==> a = b = +-3

Ответ: a = b = +-3

должно быть верно