If Adam buys 4 marbles and 5 stickers, it costs $48.70.
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 = 48.70 --- (1)
5 marbles + 4 stickers = 48.70 + 5.20 = 53.90 --- (2)
(1) + (2)
9 marbles + 9 stickers = 102.60 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 102.60 ÷ 9 = 11.40 --- (4)
Cost of 1 marble and 1 sticker = $11.40
(b)
5 marbles + 4 stickers = 53.90 --- (2)
(4)
x 4 4 marbles + 4 stickers = 4 x 11.40 = 45.60 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 53.90 - 45.60
5 marbles - 4 marbles + 4 stickers - 4 stickers = 8.30
1 marble = 8.30
Cost of 1 marble = $8.30
(c)
Substitute 1 marble = 8.30 into (4).
1 marble + 1 sticker = 11.40
8.30 + 1 sticker = 11.40
1 sticker = 11.40 - 8.30 = 3.10
Cost of 1 sticker = $3.10
Answer(s): (a) $11.40; (b) $8.30; (c) $3.10