Victoria, Ella, Gabriel and Isaiah share the same hobby of collecting stamps. The average number of stamps collected by the 4 friends is 25. Ella collected 8 more stamps than Gabriel but 12 fewer stamps than Victoria. Isaiah collected 4 stamps fewer than Gabriel. Find the average number of stamps collected by Ella, Gabriel and Isaiah. Round off your answer to the nearest whole number.
Number of stamps Gabriel collected = 1 u
Number of stamps Ella collected = 1 u + 8
Number of stamps Victoria collected = 1 u + 8 + 12 = 1 u + 20
Number of stamps Isaiah collected = 1 u - 4

Total number of stamps collected
= 4 x 25
= 100

Total number of stamps collected in units
= 1 u + 1 u + 8 + 1 u + 20 + 1 u - 4
= 4 u + 24

4 u + 24 = 100
4 u = 100 - 24 = 76

1 u = 76 ÷ 4 = 19

Total number of stamps collected by Ella, Gabriel and Isaiah
= 1 u + 8 + 1 u + 1 u - 4
= 3 u + 4
= 3 x 19 + 4
= 61

Average number of stamps collected by Ella, Gabriel and Isaiah
= 61 ÷ 3
≈ 20 (Round off to the nearest whole number.)

Answer(s): 20