Four children made the following statements.
William : Tommy is 2 kg heavier than Gavin.
Gavin : Our masses are in consecutive order.
Alexander : The average of William's mass and my mass is 43 kg.
Tommy : I am the heaviest.

What is the total mass of Alexander, Tommy and William ?
Order of the mass of 4 children:
_____ , Gavin, _____ , Tommy (Heaviest)

Total mass of Alexander and William
= 2 x 43
= 86 kg

For Alexander and William,
Mass of the lighter one = 1 u
Mass of the heavier one = 1 u + 2

Total mass of Alexander and William
= 1 u + 1 u + 2
= 2 u + 2

2 u + 2 = 86
2 u = 86 - 2
2 u = 84

1 u = 84 ÷ 2 = 42

The mass of the four children in consecutive order is 42, 43, 44 and 45.

Total mass of Alexander, Tommy and William
= 42 + 44 + 45
= 131

Answer(s): 131 kg