If Adam buys 2 stickers and 3 marbles, it costs $27.20.
If Adam buys 3 stickers and 2 marbles, he will need another $4.10.
- 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 = 27.20 --- (1)
3 stickers + 2 marbles = 27.20 + 4.10 = 31.30 --- (2)
(1) + (2)
5 stickers + 5 marbles = 58.50 --- (3)
(3)
÷ 5 1 sticker + 1 marble = 58.50 ÷ 5 = 11.70 --- (4)
Cost of 1 sticker and 1 marble = $11.70
(b)
3 stickers + 2 marbles = 31.30 --- (2)
(4)
x 2 2 stickers + 2 marbles = 2 x 11.70 = 23.40 --- (5)
(2) - (5)
3 stickers + 2 marbles - 2 stickers - 2 marbles = 31.30 - 23.40
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 = 11.70
7.90 + 1 marble = 11.70
1 marble = 11.70 - 7.90 = 3.80
Cost of 1 marble = $3.80
Answer(s): (a) $11.70; (b) $7.90; (c) $3.80