Wyatt, Hazel, Christopher and Olivia share the same hobby of collecting cards. The average number of cards collected by the 4 friends is 30. Hazel collected 9 more cards than Christopher but 14 fewer cards than Wyatt. Olivia collected 4 cards fewer than Christopher. Find the average number of cards collected by Hazel, Christopher and Olivia. Round off your answer to the nearest whole number.
Number of cards Christopher collected = 1 u
Number of cards Hazel collected = 1 u + 9
Number of cards Wyatt collected = 1 u + 9 + 14 = 1 u + 23
Number of cards Olivia collected = 1 u - 4

Total number of cards collected
= 4 x 30
= 120

Total number of cards collected in units
= 1 u + 1 u + 9 + 1 u + 23 + 1 u - 4
= 4 u + 28

4 u + 28 = 120
4 u = 120 - 28 = 92

1 u = 92 ÷ 4 = 23

Total number of cards collected by Hazel, Christopher and Olivia
= 1 u + 9 + 1 u + 1 u - 4
= 3 u + 5
= 3 x 23 + 5
= 74

Average number of cards collected by Hazel, Christopher and Olivia
= 74 ÷ 3
≈ 25 (Round off to the nearest whole number.)

Answer(s): 25