The mass of 4 children, Jane, Winnie, George and Sam were taken. Only 3 children can be weighed at one time. Jane, Winnie and George weighed a total of 48 kg. Winnie, George and Sam weighed a total of 73 kg. Jane, George and Sam weighed a total of 110 kg. Jane, Winnie, and Sam weighed a total of 117 kg. What is the average mass of the 4 children?
Jane + Winnie + George = 48 --- (1)
Winnie + George + Sam = 73 --- (2)
Jane + George + Sam = 110 --- (3)
Jane + Winnie + Sam = 117 --- (4)

(1) + (2) + (3) + (4)
3(Jane + Winnie + George + Sam) = 48 + 73 + 110 + 117
3(Jane + Winnie + George + Sam) = 348
Jane + Winnie + George + Sam = 348 ÷ 3 = 116

Total mass of the 4 children = 116

Average mass of the 4 children
= 116 ÷ 4
= 29

Answer(s): 29 kg