a + b + c + d = 5100
a = b + 450
c = d : 4
a + b = 2(c + d)
2(c + d) + c + d = 5100
3(c + d) = 5100
c + d = 5100 : 3
c + d = 1700
d = 4c
c + 4c = 1700
5c = 1700 : 5
c = 340 kg
d = 4 * 340
d = 1360 kg
a + b + 340 + 1360 = 5100
a + b = 3400
b + 450 + b = 3400
2b = 3400 - 450
b = 2950 : 2
b = 1475 kg
a = 3400 - 1475
a = 1925 kg
proba:
1925 + 1475 + 340 + 1360 = 5100 kg