Emma, Victoria, John and Christopher share the same hobby of collecting buttons. The average number of buttons collected by the 4 friends is 25. Victoria collected 7 more buttons than John but 15 fewer buttons than Emma. Christopher collected 5 buttons fewer than John. Find the average number of buttons collected by Victoria, John and Christopher. Round off your answer to the nearest whole number.
Number of buttons John collected = 1 u
Number of buttons Victoria collected = 1 u + 7
Number of buttons Emma collected = 1 u + 7 + 15 = 1 u + 22
Number of buttons Christopher collected = 1 u - 5

Total number of buttons collected
= 4 x 25
= 100

Total number of buttons collected in units
= 1 u + 1 u + 7 + 1 u + 22 + 1 u - 5
= 4 u + 24

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

1 u = 76 ÷ 4 = 19

Total number of buttons collected by Victoria, John and Christopher
= 1 u + 7 + 1 u + 1 u - 5
= 3 u + 2
= 3 x 19 + 2
= 59

Average number of buttons collected by Victoria, John and Christopher
= 59 ÷ 3
≈ 20 (Round off to the nearest whole number.)

Answer(s): 20