Hazel, Ava, Roshel and Luke share the same hobby of collecting marbles. The average number of marbles collected by the 4 friends is 26. Ava collected 7 more marbles than Roshel but 14 fewer marbles than Hazel. Luke collected 4 marbles fewer than Roshel. Find the average number of marbles collected by Ava and Luke. Round off your answer to the nearest whole number.
Number of marbles Roshel collected = 1 u
Number of marbles Ava collected = 1 u + 7
Number of marbles Hazel collected = 1 u + 7 + 14 = 1 u + 21
Number of marbles Luke collected = 1 u - 4

Total number of marbles collected
= 4 x 26
= 104

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

4 u + 24 = 104
4 u = 104 - 24 = 80

1 u = 80 ÷ 4 = 20

Total number of marbles collected by Ava and Luke
= 1 u + 7 + 1 u - 4
= 2 u + 3
= 2 x 20 + 3
= 43

Average number of marbles collected by Ava and Luke
= 43 ÷ 2
≈ 22 (Round off to the nearest whole number.)

Answer(s): 22