If Adam buys 4 stickers and 5 marbles, it costs $52.30.
If Adam buys 5 stickers and 4 marbles, he will need another $2.50.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
(a)
4 stickers + 5 marbles = 52.30 --- (1)
5 stickers + 4 marbles = 52.30 + 2.50 = 54.80 --- (2)
(1) + (2)
9 stickers + 9 marbles = 107.10 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 107.10 ÷ 9 = 11.90 --- (4)
Cost of 1 sticker and 1 marble = $11.90
(b)
5 stickers + 4 marbles = 54.80 --- (2)
(4)
x 4 4 stickers + 4 marbles = 4 x 11.90 = 47.60 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 54.80 - 47.60
5 stickers - 4 stickers + 4 marbles - 4 marbles = 7.20
1 sticker = 7.20
Cost of 1 sticker = $7.20
(c)
Substitute 1 sticker = 7.20 into (4).
1 sticker + 1 marble = 11.90
7.20 + 1 marble = 11.90
1 marble = 11.90 - 7.20 = 4.70
Cost of 1 marble = $4.70
Answer(s): (a) $11.90; (b) $7.20; (c) $4.70