The mass of 4 children, Elyse, Yoko, Perry and Rael were taken. Only 3 children can be weighed at one time. Elyse, Yoko and Perry weighed a total of 98 kg. Yoko, Perry and Rael weighed a total of 114 kg. Elyse, Perry and Rael weighed a total of 46 kg. Elyse, Yoko, and Rael weighed a total of 54 kg. What is the average mass of the 4 children?
Elyse + Yoko + Perry = 98 --- (1)
Yoko + Perry + Rael = 114 --- (2)
Elyse + Perry + Rael = 46 --- (3)
Elyse + Yoko + Rael = 54 --- (4)

(1) + (2) + (3) + (4)
3(Elyse + Yoko + Perry + Rael) = 98 + 114 + 46 + 54
3(Elyse + Yoko + Perry + Rael) = 312
Elyse + Yoko + Perry + Rael = 312 ÷ 3 = 104

Total mass of the 4 children = 104

Average mass of the 4 children
= 104 ÷ 4
= 26

Answer(s): 26 kg