If Adam buys 4 marbles and 5 stickers, it costs $53.20.
If Adam buys 5 marbles and 4 stickers, he will need another $5.20.
- 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 = 53.20 --- (1)
5 marbles + 4 stickers = 53.20 + 5.20 = 58.40 --- (2)
(1) + (2)
9 marbles + 9 stickers = 111.60 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 111.60 ÷ 9 = 12.40 --- (4)
Cost of 1 marble and 1 sticker = $12.40
(b)
5 marbles + 4 stickers = 58.40 --- (2)
(4)
x 4 4 marbles + 4 stickers = 4 x 12.40 = 49.60 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 58.40 - 49.60
5 marbles - 4 marbles + 4 stickers - 4 stickers = 8.80
1 marble = 8.80
Cost of 1 marble = $8.80
(c)
Substitute 1 marble = 8.80 into (4).
1 marble + 1 sticker = 12.40
8.80 + 1 sticker = 12.40
1 sticker = 12.40 - 8.80 = 3.60
Cost of 1 sticker = $3.60
Answer(s): (a) $12.40; (b) $8.80; (c) $3.60