Question

Докажите тождество:
1) 4(2 -3m) - (6 -m) - 2(3m + 4) = -17m -6
2) a +b - 10ab = 2a(3 - b)- 3b(a-2) - 5(ab + a + b)
3) 6(5a - 3) + (10 - 20a) - (6a -4) = 5a - (3a - (2a - 4))