problema 2
a+ b + c = 24 800 l
a + b = 17 950
b + c = 18 700
17 950 + c = 24 800
c = 24 800 - 17 950
c = 6850
b + c = 18 700
b + 6850 = 18 700
b = 18 700 - 6850
b = 11850
a + b = 17 950
a + 11 850 = 17 950
a = 17 950 - 11 850
a = 6100
verificam
6100 + 11850 + 6850 = 24 800