Question

4 boys weighed themselves in different pairs and alone. The weights of the pairs were 110kg, 112 kg, 113kg, 118kg, 121 kg, and the weight of one pair was lost. The total weight of the 4 boys was 230kg. What was the lost weight?

Answer 1

116

Explanation:

you can use variables

a+b=110

a+c=112

a+d=113

b+c=118

b+d=121

add up the weights and you get 574 kg (you need to find c+d)

3a+3b+2c+2d=574

a+b+c+d = 230 as given then you multiply by 3 so you can cancel out 3a and 3b and subtract 690-574 because we multiplied by 3

you are left with c+d=116