The average number of stickers that Charlie and Bryan have is 4.
The average number of stickers that Bryan and Adam have is 5.
The average number of stickers that Adam and Charlie have is 3.
- How many stickers does Charlie have?
- How many stickers does Bryan have?
- How many stickers does Adam have?
(a)
Let the number of stickers that Charlie has be C.
Let the number of stickers that Bryan has be B.
Let the number of stickers that Adam has be A.
C + B = 2 x 4 = 8 --- (1)
B + A = 2 x 5 = 10 --- (2)
C + A = 2 x 3 = 6 --- (3)
(C + B) + (B + A) + (C + A) = 8 + 10 + 6
2 x (C + B + A) = 24
C + B + A = 24 ÷ 2
C + B + A = 12 --- (4)
Substitute (2) into (4).
C + B + A = 12
C + 10 = 12
C = 12 - 10 = 2
Number of stickers that Charlie has = 2
(b)
Substitute C = 2 into (1).
C + B = 8
2 + B = 8
B = 8 - 2 = 6
Number of stickers that Bryan has = 6
(c)
Substitute Bryan's stickers = 6 into (2).
B + A = 10
6 + A = 10
A = 10 - 6 = 4
Number of stickers that Adam has = 4
Answer(s): (a) 2; (b) 6; (c) 4