Tiga pelajar toni, rani dan rehan mengukur berat badan secara berpasangan. Berat badan toni dan rani 120kg. Rani dan rehan 110kg serta toni dan rehan 100kg. Hit

Toni = a
Rani = b
Rehan = c

a+b = 120
b+c = 110
a+c = 100

a = 120-b
Maka :
a+c = 100
120-b+c = 100
-b+c = -20

b+c = 110
-b+c = -20
-------------(ditambah)
2c = 90
c = 45 kg

a+c = 100
a = 100-45
a = 55 kg

b+c = 110
b = 110-45
b = 65