The mass of 4 children, Shannon, Victoria, Carl and Andy were taken. Only 3 children can be weighed at one time. Shannon, Victoria and Carl weighed a total of 95 kg. Victoria, Carl and Andy weighed a total of 102 kg. Shannon, Carl and Andy weighed a total of 50 kg. Shannon, Victoria, and Andy weighed a total of 65 kg. What is the average mass of the 4 children?
Shannon + Victoria + Carl = 95 --- (1)
Victoria + Carl + Andy = 102 --- (2)
Shannon + Carl + Andy = 50 --- (3)
Shannon + Victoria + Andy = 65 --- (4)

(1) + (2) + (3) + (4)
3(Shannon + Victoria + Carl + Andy) = 95 + 102 + 50 + 65
3(Shannon + Victoria + Carl + Andy) = 312
Shannon + Victoria + Carl + Andy = 312 ÷ 3 = 104

Total mass of the 4 children = 104

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

Answer(s): 26 kg