If Adam buys 2 marbles and 3 stickers, it costs $26.90.
If Adam buys 3 marbles and 2 stickers, he will need another $1.70.
- 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 = 26.90 --- (1)
3 marbles + 2 stickers = 26.90 + 1.70 = 28.60 --- (2)
(1) + (2)
5 marbles + 5 stickers = 55.50 --- (3)
(3)
÷ 5 1 marble + 1 sticker = 55.50 ÷ 5 = 11.10 --- (4)
Cost of 1 marble and 1 sticker = $11.10
(b)
3 marbles + 2 stickers = 28.60 --- (2)
(4)
x 2 2 marbles + 2 stickers = 2 x 11.10 = 22.20 --- (5)
(2) - (5)
3 marbles + 2 stickers - 2 marbles - 2 stickers = 28.60 - 22.20
3 marbles - 2 marbles + 2 stickers - 2 stickers = 6.40
1 marble = 6.40
Cost of 1 marble = $6.40
(c)
Substitute 1 marble = 6.40 into (4).
1 marble + 1 sticker = 11.10
6.40 + 1 sticker = 11.10
1 sticker = 11.10 - 6.40 = 4.70
Cost of 1 sticker = $4.70
Answer(s): (a) $11.10; (b) $6.40; (c) $4.70