If Adam buys 4 marbles and 5 stickers, it costs $54.70.
If Adam buys 5 marbles and 4 stickers, he will need another $0.40.
- Find the cost of 1 marble and 1 sticker.
- Find the cost of 1 marble.
- Find the cost of 1 sticker.
(a)
4 marbles + 5 stickers = 54.70 --- (1)
5 marbles + 4 stickers = 54.70 + 0.40 = 55.10 --- (2)
(1) + (2)
9 marbles + 9 stickers = 109.80 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 109.80 ÷ 9 = 12.20 --- (4)
Cost of 1 marble and 1 sticker = $12.20
(b)
5 marbles + 4 stickers = 55.10 --- (2)
(4)
x 4 4 marbles + 4 stickers = 4 x 12.20 = 48.80 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 55.10 - 48.80
5 marbles - 4 marbles + 4 stickers - 4 stickers = 6.30
1 marble = 6.30
Cost of 1 marble = $6.30
(c)
Substitute 1 marble = 6.30 into (4).
1 marble + 1 sticker = 12.20
6.30 + 1 sticker = 12.20
1 sticker = 12.20 - 6.30 = 5.90
Cost of 1 sticker = $5.90
Answer(s): (a) $12.20; (b) $6.30; (c) $5.90