If Adam buys 4 stickers and 5 marbles, it costs $50.60.
If Adam buys 5 stickers and 4 marbles, he will need another $3.20.
- 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 = 50.60 --- (1)
5 stickers + 4 marbles = 50.60 + 3.20 = 53.80 --- (2)
(1) + (2)
9 stickers + 9 marbles = 104.40 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 104.40 ÷ 9 = 11.60 --- (4)
Cost of 1 sticker and 1 marble = $11.60
(b)
5 stickers + 4 marbles = 53.80 --- (2)
(4)
x 4 4 stickers + 4 marbles = 4 x 11.60 = 46.40 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 53.80 - 46.40
5 stickers - 4 stickers + 4 marbles - 4 marbles = 7.40
1 sticker = 7.40
Cost of 1 sticker = $7.40
(c)
Substitute 1 sticker = 7.40 into (4).
1 sticker + 1 marble = 11.60
7.40 + 1 marble = 11.60
1 marble = 11.60 - 7.40 = 4.20
Cost of 1 marble = $4.20
Answer(s): (a) $11.60; (b) $7.40; (c) $4.20