John, Julie, Hazel and Josiah share the same hobby of collecting cards. The average number of cards collected by the 4 friends is 23. Julie collected 6 more cards than Hazel but 16 fewer cards than John. Josiah collected 4 cards fewer than Hazel. Find the average number of cards collected by Julie, Hazel and Josiah. Round off your answer to the nearest whole number.
Number of cards Hazel collected = 1 u
Number of cards Julie collected = 1 u + 6
Number of cards John collected = 1 u + 6 + 16 = 1 u + 22
Number of cards Josiah collected = 1 u - 4

Total number of cards collected
= 4 x 23
= 92

Total number of cards collected in units
= 1 u + 1 u + 6 + 1 u + 22 + 1 u - 4
= 4 u + 24

4 u + 24 = 92
4 u = 92 - 24 = 68

1 u = 68 ÷ 4 = 17

Total number of cards collected by Julie, Hazel and Josiah
= 1 u + 6 + 1 u + 1 u - 4
= 3 u + 2
= 3 x 17 + 2
= 53

Average number of cards collected by Julie, Hazel and Josiah
= 53 ÷ 3
≈ 18 (Round off to the nearest whole number.)

Answer(s): 18