Sofia, Abigail, Nora and Salik share the same hobby of collecting coins. The average number of coins collected by the 4 friends is 23. Abigail collected 7 more coins than Nora but 16 fewer coins than Sofia. Salik collected 2 coins fewer than Nora. Find the average number of coins collected by Abigail and Salik. Round off your answer to the nearest whole number.
Number of coins Nora collected = 1 u
Number of coins Abigail collected = 1 u + 7
Number of coins Sofia collected = 1 u + 7 + 16 = 1 u + 23
Number of coins Salik collected = 1 u - 2

Total number of coins collected
= 4 x 23
= 92

Total number of coins collected in units
= 1 u + 1 u + 7 + 1 u + 23 + 1 u - 2
= 4 u + 28

4 u + 28 = 92
4 u = 92 - 28 = 64

1 u = 64 ÷ 4 = 16

Total number of coins collected by Abigail and Salik
= 1 u + 7 + 1 u - 2
= 2 u + 5
= 2 x 16 + 5
= 37

Average number of coins collected by Abigail and Salik
= 37 ÷ 2
≈ 19 (Round off to the nearest whole number.)

Answer(s): 19