The mass of 4 children, Jaslyn, Jade, Ethan and Tom were taken. Only 3 children can be weighed at one time. Jaslyn, Jade and Ethan weighed a total of 97 kg. Jade, Ethan and Tom weighed a total of 82 kg. Jaslyn, Ethan and Tom weighed a total of 135 kg. Jaslyn, Jade, and Tom weighed a total of 46 kg. What is the average mass of the 4 children?
Jaslyn + Jade + Ethan = 97 --- (1)
Jade + Ethan + Tom = 82 --- (2)
Jaslyn + Ethan + Tom = 135 --- (3)
Jaslyn + Jade + Tom = 46 --- (4)

(1) + (2) + (3) + (4)
3(Jaslyn + Jade + Ethan + Tom) = 97 + 82 + 135 + 46
3(Jaslyn + Jade + Ethan + Tom) = 360
Jaslyn + Jade + Ethan + Tom = 360 ÷ 3 = 120

Total mass of the 4 children = 120

Average mass of the 4 children
= 120 ÷ 4
= 30

Answer(s): 30 kg