Tommy, Ava, Elijah and Emma share the same hobby of collecting erasers. The average number of erasers collected by the 4 friends is 24. Ava collected 9 more erasers than Elijah but 12 fewer erasers than Tommy. Emma collected 2 erasers fewer than Elijah. Find the average number of erasers collected by Ava, Elijah and Emma. Round off your answer to the nearest whole number.
Number of erasers Elijah collected = 1 u
Number of erasers Ava collected = 1 u + 9
Number of erasers Tommy collected = 1 u + 9 + 12 = 1 u + 21
Number of erasers Emma collected = 1 u - 2

Total number of erasers collected
= 4 x 24
= 96

Total number of erasers collected in units
= 1 u + 1 u + 9 + 1 u + 21 + 1 u - 2
= 4 u + 28

4 u + 28 = 96
4 u = 96 - 28 = 68

1 u = 68 ÷ 4 = 17

Total number of erasers collected by Ava, Elijah and Emma
= 1 u + 9 + 1 u + 1 u - 2
= 3 u + 7
= 3 x 17 + 7
= 58

Average number of erasers collected by Ava, Elijah and Emma
= 58 ÷ 3
≈ 19 (Round off to the nearest whole number.)

Answer(s): 19