If Adam buys 2 marbles and 3 stickers, it costs $31.20.
If Adam buys 3 marbles and 2 stickers, he will have $7.90 left.
- Find the cost of 1 marble and 1 sticker.
- Find the cost of 1 marble.
- Find the cost of 1 sticker.
(a)
2 marbles + 3 stickers = 31.20 --- (1)
3 marbles + 2 stickers = 31.20 - 7.90 = 23.30 --- (2)
(1) + (2)
5 marbles + 5 stickers = 54.50 --- (3)
(3)
÷ 5 1 marble + 1 sticker = 54.50 ÷ 5 = 10.90 --- (4)
Cost of 1 marble and 1 sticker = $10.90
(b)
(4)
x 2 2 marbles + 2 stickers = 2 x 10.90 = 21.80 --- (5)
(2) - (5)
3 marbles + 2 stickers - 2 marbles - 2 stickers = 23.30 - 21.80
3 marbles - 2 marbles - 2 stickers + 2 stickers = 1.50
1 marble = 1.50
Cost of 1 marble = $1.50
(c)
Substitute 1 marble = 1.50 into (4).
1 marble + 1 sticker = 10.90
1.50 + 1 sticker = 10.90
1 sticker = 10.90 - 1.50 = 9.40
Cost of 1 sticker = $9.40
Answer(s): (a) $10.90; (b) $1.50; (c) $9.40