If Adam buys 2 stickers and 3 marbles, it costs $32.40.
If Adam buys 3 stickers and 2 marbles, he will need another $2.70.
- 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 = 32.40 --- (1)
3 stickers + 2 marbles = 32.40 + 2.70 = 35.10 --- (2)
(1) + (2)
5 stickers + 5 marbles = 67.50 --- (3)
(3)
÷ 5 1 sticker + 1 marble = 67.50 ÷ 5 = 13.50 --- (4)
Cost of 1 sticker and 1 marble = $13.50
(b)
3 stickers + 2 marbles = 35.10 --- (2)
(4)
x 2 2 stickers + 2 marbles = 2 x 13.50 = 270 --- (5)
(2) - (5)
3 stickers + 2 marbles - 2 stickers - 2 marbles = 35.10 - 270
3 stickers - 2 stickers + 2 marbles - 2 marbles = 8.10
1 sticker = 8.10
Cost of 1 sticker = $8.10
(c)
Substitute 1 sticker = 8.10 into (4).
1 sticker + 1 marble = 13.50
8.10 + 1 marble = 13.50
1 marble = 13.50 - 8.10 = 5.40
Cost of 1 marble = $5.40
Answer(s): (a) $13.50; (b) $8.10; (c) $5.40