The mass of 4 children, Jaslyn, Opal, Andy and Flynn were taken. Only 3 children can be weighed at one time. Jaslyn, Opal and Andy weighed a total of 132 kg. Opal, Andy and Flynn weighed a total of 118 kg. Jaslyn, Andy and Flynn weighed a total of 122 kg. Jaslyn, Opal, and Flynn weighed a total of 144 kg. What is the average mass of the 4 children?
Jaslyn + Opal + Andy = 132 --- (1)
Opal + Andy + Flynn = 118 --- (2)
Jaslyn + Andy + Flynn = 122 --- (3)
Jaslyn + Opal + Flynn = 144 --- (4)

(1) + (2) + (3) + (4)
3(Jaslyn + Opal + Andy + Flynn) = 132 + 118 + 122 + 144
3(Jaslyn + Opal + Andy + Flynn) = 516
Jaslyn + Opal + Andy + Flynn = 516 ÷ 3 = 172

Total mass of the 4 children = 172

Average mass of the 4 children
= 172 ÷ 4
= 43

Answer(s): 43 kg