The average number of marbles that Bryan and Adam have is 28.
The average number of marbles that Bryan and Charlie have is 58.
The number of marbles that Adam has is ⁴₉ as many as Charlie.

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

(a)
Number of marbles that Bryan and Adam has
= 2 x 28
= 56

Number of marbles that Bryan and Charlie has
= 2 x 58
= 116

Number of marbles that Adam has = 4 u
Number of marbles that Charlie has = 9 u

Let the number of Bryan's marbles be B.
Let the number of Adam's marbles be A.
Let the number of Charlie's marbles be C.


B + A = 56
B + 4 u = 56 --- (1)

B + C = 116
B + 9 u = 116 --- (2)

(2) - (1)
(B + 9 u) - (B + 4 u ) = 116 - 56
B + 9 u - B - 4 u = 60
B - B + 9 u - 4 u = 60

5 u = 60

1 u = 60 ÷ 5 = 12

Substitute 1 u = 12 into (1).
B + 4 x 12 = 56
B + 48 = 56
B = 56 - 48 = 8

Number of marbles that Bryan has = 8

(b)
Number of marbles that Adam has
= 4 u
= 4 x 12
= 48

(c)
Number of marbles that Charlie has
= 9 u
= 9 x 12
= 108

Answer(s): (a) 8; (b) 48; (c) 108