If Adam buys 3 marbles and 4 stickers, it costs $470.
If Adam buys 4 marbles and 3 stickers, he will need another $2.60.
- 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 = 470 --- (1)
4 marbles + 3 stickers = 470 + 2.60 = 49.60 --- (2)
(1) + (2)
7 marbles + 7 stickers = 96.60 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 96.60 ÷ 7 = 13.80 --- (4)
Cost of 1 marble and 1 sticker = $13.80
(b)
4 marbles + 3 stickers = 49.60 --- (2)
(4)
x 3 3 marbles + 3 stickers = 3 x 13.80 = 41.40 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 49.60 - 41.40
4 marbles - 3 marbles + 3 stickers - 3 stickers = 8.20
1 marble = 8.20
Cost of 1 marble = $8.20
(c)
Substitute 1 marble = 8.20 into (4).
1 marble + 1 sticker = 13.80
8.20 + 1 sticker = 13.80
1 sticker = 13.80 - 8.20 = 5.60
Cost of 1 sticker = $5.60
Answer(s): (a) $13.80; (b) $8.20; (c) $5.60