Gavin, Elizabeth, Isaiah and Claire share the same hobby of collecting erasers. The average number of erasers collected by the 4 friends is 28. Elizabeth collected 8 more erasers than Isaiah but 16 fewer erasers than Gavin. Claire collected 4 erasers fewer than Isaiah. Find the average number of erasers collected by Elizabeth, Isaiah and Claire. Round off your answer to the nearest whole number.
Number of erasers Isaiah collected = 1 u
Number of erasers Elizabeth collected = 1 u + 8
Number of erasers Gavin collected = 1 u + 8 + 16 = 1 u + 24
Number of erasers Claire collected = 1 u - 4

Total number of erasers collected
= 4 x 28
= 112

Total number of erasers collected in units
= 1 u + 1 u + 8 + 1 u + 24 + 1 u - 4
= 4 u + 28

4 u + 28 = 112
4 u = 112 - 28 = 84

1 u = 84 ÷ 4 = 21

Total number of erasers collected by Elizabeth, Isaiah and Claire
= 1 u + 8 + 1 u + 1 u - 4
= 3 u + 4
= 3 x 21 + 4
= 67

Average number of erasers collected by Elizabeth, Isaiah and Claire
= 67 ÷ 3
≈ 22 (Round off to the nearest whole number.)

Answer(s): 22