If Adam buys 4 marbles and 5 stickers, it costs $52.90.
If Adam buys 5 marbles and 4 stickers, he will need another $4.90.
- 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 = 52.90 --- (1)
5 marbles + 4 stickers = 52.90 + 4.90 = 57.80 --- (2)
(1) + (2)
9 marbles + 9 stickers = 110.70 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 110.70 ÷ 9 = 12.30 --- (4)
Cost of 1 marble and 1 sticker = $12.30
(b)
5 marbles + 4 stickers = 57.80 --- (2)
(4)
x 4 4 marbles + 4 stickers = 4 x 12.30 = 49.20 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 57.80 - 49.20
5 marbles - 4 marbles + 4 stickers - 4 stickers = 8.60
1 marble = 8.60
Cost of 1 marble = $8.60
(c)
Substitute 1 marble = 8.60 into (4).
1 marble + 1 sticker = 12.30
8.60 + 1 sticker = 12.30
1 sticker = 12.30 - 8.60 = 3.70
Cost of 1 sticker = $3.70
Answer(s): (a) $12.30; (b) $8.60; (c) $3.70