If Adam buys 4 marbles and 5 stickers, it costs $58.50.
If Adam buys 5 marbles and 4 stickers, he will need another $3.60.
- 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 = 58.50 --- (1)
5 marbles + 4 stickers = 58.50 + 3.60 = 62.10 --- (2)
(1) + (2)
9 marbles + 9 stickers = 120.60 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 120.60 ÷ 9 = 13.40 --- (4)
Cost of 1 marble and 1 sticker = $13.40
(b)
5 marbles + 4 stickers = 62.10 --- (2)
(4)
x 4 4 marbles + 4 stickers = 4 x 13.40 = 53.60 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 62.10 - 53.60
5 marbles - 4 marbles + 4 stickers - 4 stickers = 8.50
1 marble = 8.50
Cost of 1 marble = $8.50
(c)
Substitute 1 marble = 8.50 into (4).
1 marble + 1 sticker = 13.40
8.50 + 1 sticker = 13.40
1 sticker = 13.40 - 8.50 = 4.90
Cost of 1 sticker = $4.90
Answer(s): (a) $13.40; (b) $8.50; (c) $4.90