If Adam buys 2 marbles and 3 stickers, it costs $28.80.
If Adam buys 3 marbles and 2 stickers, he will need another $3.90.
- Find the cost of 1 marble and 1 sticker.
- Find the cost of 1 marble.
- Find the cost of 1 sticker.
(a)
2 marbles + 3 stickers = 28.80 --- (1)
3 marbles + 2 stickers = 28.80 + 3.90 = 32.70 --- (2)
(1) + (2)
5 marbles + 5 stickers = 61.50 --- (3)
(3)
÷ 5 1 marble + 1 sticker = 61.50 ÷ 5 = 12.30 --- (4)
Cost of 1 marble and 1 sticker = $12.30
(b)
3 marbles + 2 stickers = 32.70 --- (2)
(4)
x 2 2 marbles + 2 stickers = 2 x 12.30 = 24.60 --- (5)
(2) - (5)
3 marbles + 2 stickers - 2 marbles - 2 stickers = 32.70 - 24.60
3 marbles - 2 marbles + 2 stickers - 2 stickers = 8.10
1 marble = 8.10
Cost of 1 marble = $8.10
(c)
Substitute 1 marble = 8.10 into (4).
1 marble + 1 sticker = 12.30
8.10 + 1 sticker = 12.30
1 sticker = 12.30 - 8.10 = 4.20
Cost of 1 sticker = $4.20
Answer(s): (a) $12.30; (b) $8.10; (c) $4.20