b) ab - ac = 45 si b - c = 9
a(b - c) = 45
a * 9 = 45
a = 45/9
a = 5
c) ab + ac + 70 = 170 si a = 25
a(b + c) = 170 - 70
25 * (b + c) = 100
b + c = 100/25
b + c = 4
d) ab - ac - 48 = 2 si a = 10
a(b - c) = 48 + 2
10 * (b - c) = 50
b - c = 50/10
b - c = 5