If Adam buys 3 marbles and 4 stickers, it costs $46.20.
If Adam buys 4 marbles and 3 stickers, he will have $70 left.
- 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 = 46.20 --- (1)
4 marbles + 3 stickers = 46.20 - 70 = 39.20 --- (2)
(1) + (2)
7 marbles + 7 stickers = 85.40 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 85.40 ÷ 7 = 12.20 --- (4)
Cost of 1 marble and 1 sticker = $12.20
(b)
(4)
x 3 3 marbles + 3 stickers = 3 x 12.20 = 36.60 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 39.20 - 36.60
4 marbles - 3 marbles - 3 stickers + 3 stickers = 2.60
1 marble = 2.60
Cost of 1 marble = $2.60
(c)
Substitute 1 marble = 2.60 into (4).
1 marble + 1 sticker = 12.20
2.60 + 1 sticker = 12.20
1 sticker = 12.20 - 2.60 = 9.60
Cost of 1 sticker = $9.60
Answer(s): (a) $12.20; (b) $2.60; (c) $9.60