Jonathan, Mia, Salik and Aubrey share the same hobby of collecting stamps. The average number of stamps collected by the 4 friends is 28. Mia collected 7 more stamps than Salik but 14 fewer stamps than Jonathan. Aubrey collected 4 stamps fewer than Salik. Find the average number of stamps collected by Mia and Aubrey. Round off your answer to the nearest whole number.
Number of stamps Salik collected = 1 u
Number of stamps Mia collected = 1 u + 7
Number of stamps Jonathan collected = 1 u + 7 + 14 = 1 u + 21
Number of stamps Aubrey collected = 1 u - 4

Total number of stamps collected
= 4 x 28
= 112

Total number of stamps collected in units
= 1 u + 1 u + 7 + 1 u + 21 + 1 u - 4
= 4 u + 24

4 u + 24 = 112
4 u = 112 - 24 = 88

1 u = 88 ÷ 4 = 22

Total number of stamps collected by Mia and Aubrey
= 1 u + 7 + 1 u - 4
= 2 u + 3
= 2 x 22 + 3
= 47

Average number of stamps collected by Mia and Aubrey
= 47 ÷ 2
≈ 24 (Round off to the nearest whole number.)

Answer(s): 24