If Adam buys 2 stickers and 3 marbles, it costs $23.60.
If Adam buys 3 stickers and 2 marbles, he will need another $2.30.
- 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 = 23.60 --- (1)
3 stickers + 2 marbles = 23.60 + 2.30 = 25.90 --- (2)
(1) + (2)
5 stickers + 5 marbles = 49.50 --- (3)
(3)
÷ 5 1 sticker + 1 marble = 49.50 ÷ 5 = 9.90 --- (4)
Cost of 1 sticker and 1 marble = $9.90
(b)
3 stickers + 2 marbles = 25.90 --- (2)
(4)
x 2 2 stickers + 2 marbles = 2 x 9.90 = 19.80 --- (5)
(2) - (5)
3 stickers + 2 marbles - 2 stickers - 2 marbles = 25.90 - 19.80
3 stickers - 2 stickers + 2 marbles - 2 marbles = 6.10
1 sticker = 6.10
Cost of 1 sticker = $6.10
(c)
Substitute 1 sticker = 6.10 into (4).
1 sticker + 1 marble = 9.90
6.10 + 1 marble = 9.90
1 marble = 9.90 - 6.10 = 3.80
Cost of 1 marble = $3.80
Answer(s): (a) $9.90; (b) $6.10; (c) $3.80