If Adam buys 3 marbles and 4 stickers, it costs $40.60.
If Adam buys 4 marbles and 3 stickers, he will need another $1.40.
- 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 = 40.60 --- (1)
4 marbles + 3 stickers = 40.60 + 1.40 = 420 --- (2)
(1) + (2)
7 marbles + 7 stickers = 82.60 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 82.60 ÷ 7 = 11.80 --- (4)
Cost of 1 marble and 1 sticker = $11.80
(b)
4 marbles + 3 stickers = 420 --- (2)
(4)
x 3 3 marbles + 3 stickers = 3 x 11.80 = 35.40 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 420 - 35.40
4 marbles - 3 marbles + 3 stickers - 3 stickers = 6.60
1 marble = 6.60
Cost of 1 marble = $6.60
(c)
Substitute 1 marble = 6.60 into (4).
1 marble + 1 sticker = 11.80
6.60 + 1 sticker = 11.80
1 sticker = 11.80 - 6.60 = 5.20
Cost of 1 sticker = $5.20
Answer(s): (a) $11.80; (b) $6.60; (c) $5.20