If Adam buys 3 marbles and 4 stickers, it costs $34.10.
If Adam buys 4 marbles and 3 stickers, he will have $4.50 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 = 34.10 --- (1)
4 marbles + 3 stickers = 34.10 - 4.50 = 29.60 --- (2)
(1) + (2)
7 marbles + 7 stickers = 63.70 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 63.70 ÷ 7 = 9.10 --- (4)
Cost of 1 marble and 1 sticker = $9.10
(b)
(4)
x 3 3 marbles + 3 stickers = 3 x 9.10 = 27.30 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 29.60 - 27.30
4 marbles - 3 marbles - 3 stickers + 3 stickers = 2.30
1 marble = 2.30
Cost of 1 marble = $2.30
(c)
Substitute 1 marble = 2.30 into (4).
1 marble + 1 sticker = 9.10
2.30 + 1 sticker = 9.10
1 sticker = 9.10 - 2.30 = 6.80
Cost of 1 sticker = $6.80
Answer(s): (a) $9.10; (b) $2.30; (c) $6.80