If Adam buys 4 marbles and 5 stickers, it costs $50.40.
If Adam buys 5 marbles and 4 stickers, he will need another $0.90.
- 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 = 50.40 --- (1)
5 marbles + 4 stickers = 50.40 + 0.90 = 51.30 --- (2)
(1) + (2)
9 marbles + 9 stickers = 101.70 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 101.70 ÷ 9 = 11.30 --- (4)
Cost of 1 marble and 1 sticker = $11.30
(b)
5 marbles + 4 stickers = 51.30 --- (2)
(4)
x 4 4 marbles + 4 stickers = 4 x 11.30 = 45.20 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 51.30 - 45.20
5 marbles - 4 marbles + 4 stickers - 4 stickers = 6.10
1 marble = 6.10
Cost of 1 marble = $6.10
(c)
Substitute 1 marble = 6.10 into (4).
1 marble + 1 sticker = 11.30
6.10 + 1 sticker = 11.30
1 sticker = 11.30 - 6.10 = 5.20
Cost of 1 sticker = $5.20
Answer(s): (a) $11.30; (b) $6.10; (c) $5.20