If Adam buys 3 marbles and 4 stickers, it costs $42.30.
If Adam buys 4 marbles and 3 stickers, he will need another $3.60.
- Find the cost of 1 marble and 1 sticker.
- Find the cost of 1 marble.
- Find the cost of 1 sticker.
(a)
3 marbles + 4 stickers = 42.30 --- (1)
4 marbles + 3 stickers = 42.30 + 3.60 = 45.90 --- (2)
(1) + (2)
7 marbles + 7 stickers = 88.20 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 88.20 ÷ 7 = 12.60 --- (4)
Cost of 1 marble and 1 sticker = $12.60
(b)
4 marbles + 3 stickers = 45.90 --- (2)
(4)
x 3 3 marbles + 3 stickers = 3 x 12.60 = 37.80 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 45.90 - 37.80
4 marbles - 3 marbles + 3 stickers - 3 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 = 12.60
8.10 + 1 sticker = 12.60
1 sticker = 12.60 - 8.10 = 4.50
Cost of 1 sticker = $4.50
Answer(s): (a) $12.60; (b) $8.10; (c) $4.50