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

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

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

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

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

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

B = 18 - 16 = 2

Number of stickers that Bryan has = 2

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

A = 8 - 2 = 6

Number of stickers that Adam has = 6

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

C = 16 - 6 = 10

Number of stickers that Charlie has = 10

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