If Adam buys 4 stickers and 5 marbles, it costs $55.40.
If Adam buys 5 stickers and 4 marbles, he will need another $1.70.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
(a)
4 stickers + 5 marbles = 55.40 --- (1)
5 stickers + 4 marbles = 55.40 + 1.70 = 57.10 --- (2)
(1) + (2)
9 stickers + 9 marbles = 112.50 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 112.50 ÷ 9 = 12.50 --- (4)
Cost of 1 sticker and 1 marble = $12.50
(b)
5 stickers + 4 marbles = 57.10 --- (2)
(4)
x 4 4 stickers + 4 marbles = 4 x 12.50 = 500 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 57.10 - 500
5 stickers - 4 stickers + 4 marbles - 4 marbles = 7.10
1 sticker = 7.10
Cost of 1 sticker = $7.10
(c)
Substitute 1 sticker = 7.10 into (4).
1 sticker + 1 marble = 12.50
7.10 + 1 marble = 12.50
1 marble = 12.50 - 7.10 = 5.40
Cost of 1 marble = $5.40
Answer(s): (a) $12.50; (b) $7.10; (c) $5.40