If Adam buys 2 stickers and 3 marbles, it costs $28.40.
If Adam buys 3 stickers and 2 marbles, he will need another $3.70.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
(a)
2 stickers + 3 marbles = 28.40 --- (1)
3 stickers + 2 marbles = 28.40 + 3.70 = 32.10 --- (2)
(1) + (2)
5 stickers + 5 marbles = 60.50 --- (3)
(3)
÷ 5 1 sticker + 1 marble = 60.50 ÷ 5 = 12.10 --- (4)
Cost of 1 sticker and 1 marble = $12.10
(b)
3 stickers + 2 marbles = 32.10 --- (2)
(4)
x 2 2 stickers + 2 marbles = 2 x 12.10 = 24.20 --- (5)
(2) - (5)
3 stickers + 2 marbles - 2 stickers - 2 marbles = 32.10 - 24.20
3 stickers - 2 stickers + 2 marbles - 2 marbles = 7.90
1 sticker = 7.90
Cost of 1 sticker = $7.90
(c)
Substitute 1 sticker = 7.90 into (4).
1 sticker + 1 marble = 12.10
7.90 + 1 marble = 12.10
1 marble = 12.10 - 7.90 = 4.20
Cost of 1 marble = $4.20
Answer(s): (a) $12.10; (b) $7.90; (c) $4.20