Aria, Noah, Riordan and Hannah share the same hobby of collecting pens. The average number of pens collected by the 4 friends is 26. Noah collected 7 more pens than Riordan but 16 fewer pens than Aria. Hannah collected 2 pens fewer than Riordan. Find the average number of pens collected by Noah and Hannah. Round off your answer to the nearest whole number.
Number of pens Riordan collected = 1 u
Number of pens Noah collected = 1 u + 7
Number of pens Aria collected = 1 u + 7 + 16 = 1 u + 23
Number of pens Hannah collected = 1 u - 2

Total number of pens collected
= 4 x 26
= 104

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

4 u + 28 = 104
4 u = 104 - 28 = 76

1 u = 76 ÷ 4 = 19

Total number of pens collected by Noah and Hannah
= 1 u + 7 + 1 u - 2
= 2 u + 5
= 2 x 19 + 5
= 43

Average number of pens collected by Noah and Hannah
= 43 ÷ 2
≈ 22 (Round off to the nearest whole number.)

Answer(s): 22