The mass of 4 children, Kimberly, Barbara, David and Glen were taken. Only 3 children can be weighed at one time. Kimberly, Barbara and David weighed a total of 52 kg. Barbara, David and Glen weighed a total of 126 kg. Kimberly, David and Glen weighed a total of 94 kg. Kimberly, Barbara, and Glen weighed a total of 52 kg. What is the average mass of the 4 children?
Kimberly + Barbara + David = 52 --- (1)
Barbara + David + Glen = 126 --- (2)
Kimberly + David + Glen = 94 --- (3)
Kimberly + Barbara + Glen = 52 --- (4)

(1) + (2) + (3) + (4)
3(Kimberly + Barbara + David + Glen) = 52 + 126 + 94 + 52
3(Kimberly + Barbara + David + Glen) = 324
Kimberly + Barbara + David + Glen = 324 ÷ 3 = 108

Total mass of the 4 children = 108

Average mass of the 4 children
= 108 ÷ 4
= 27

Answer(s): 27 kg