Layla, Sophia, Rachel and Gabriel share the same hobby of collecting buttons. The average number of buttons collected by the 4 friends is 23. Sophia collected 7 more buttons than Rachel but 16 fewer buttons than Layla. Gabriel collected 2 buttons fewer than Rachel. Find the average number of buttons collected by Sophia and Gabriel. Round off your answer to the nearest whole number.
Number of buttons Rachel collected = 1 u
Number of buttons Sophia collected = 1 u + 7
Number of buttons Layla collected = 1 u + 7 + 16 = 1 u + 23
Number of buttons Gabriel collected = 1 u - 2

Total number of buttons collected
= 4 x 23
= 92

Total number of buttons 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 buttons collected by Sophia and Gabriel
= 1 u + 7 + 1 u - 2
= 2 u + 5
= 2 x 16 + 5
= 37

Average number of buttons collected by Sophia and Gabriel
= 37 ÷ 2
≈ 19 (Round off to the nearest whole number.)

Answer(s): 19