Four children made the following statements.
Jeremiah : The average of Sebastian's mass and my mass is 43 kg.
Ava : I am the heaviest.
Sebastian : William is 2 kg lighter than Ava.
William : Our masses are in consecutive order.

What is the total mass of Jeremiah, Ava and Sebastian ?
Order of the mass of 4 children:
_____ , William, _____ , Ava (Heaviest)

Total mass of Jeremiah and Sebastian 
= 2 x 43
= 86 kg

For Jeremiah and Sebastian,
Mass of the lighter one = 1 u
Mass of the heavier one = 1 u + 2

Total mass of Jeremiah and Sebastian
= 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 Jeremiah, Ava and Sebastian
= 42 + 44 + 45
= 131

Answer(s): 131 kg