The average number of stickers that Bryan and Charlie have is 4.
The average number of stickers that Charlie and Adam have is 8.
The average number of stickers that Adam and Bryan have is 6.

1. How many stickers does Bryan have?
2. How many stickers does Charlie have?
3. How many stickers does Adam have?

(a)
Let the number of stickers that Bryan has be B.
Let the number of stickers that Charlie has be C.
Let the number of stickers that Adam has be A.

B + C = 2 x 4 = 8 --- (1)
C + A = 2 x 8 = 16 --- (2)
B + A = 2 x 6 = 12 --- (3)

(B + C) + (C + A) + (B + A) = 8 + 16 + 12
2 x (B + C + A) = 36
B + C + A = 36 ÷ 2
B + C + A = 18 --- (4)

Substitute (2) into (4).
B + C + A = 18
B + 16 = 18

B = 18 - 16 = 2

Number of stickers that Bryan has = 2

(b)
Substitute B = 2 into (1).
B + C = 8
2 + C = 8 

C = 8 - 2 = 6

Number of stickers that Charlie has = 6

(c)
Substitute Charlie's stickers = 6 into (2).
C + A = 16
6 + A = 16

A = 16 - 6 = 10

Number of stickers that Adam has = 10

Answer(s): (a) 2; (b) 6; (c) 10