If Adam buys 2 stickers and 3 marbles, it costs $31.40.
If Adam buys 3 stickers and 2 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)
2 stickers + 3 marbles = 31.40 --- (1)
3 stickers + 2 marbles = 31.40 + 1.70 = 33.10 --- (2)
(1) + (2)
5 stickers + 5 marbles = 64.50 --- (3)
(3)
÷ 5 1 sticker + 1 marble = 64.50 ÷ 5 = 12.90 --- (4)
Cost of 1 sticker and 1 marble = $12.90
(b)
3 stickers + 2 marbles = 33.10 --- (2)
(4)
x 2 2 stickers + 2 marbles = 2 x 12.90 = 25.80 --- (5)
(2) - (5)
3 stickers + 2 marbles - 2 stickers - 2 marbles = 33.10 - 25.80
3 stickers - 2 stickers + 2 marbles - 2 marbles = 7.30
1 sticker = 7.30
Cost of 1 sticker = $7.30
(c)
Substitute 1 sticker = 7.30 into (4).
1 sticker + 1 marble = 12.90
7.30 + 1 marble = 12.90
1 marble = 12.90 - 7.30 = 5.60
Cost of 1 marble = $5.60
Answer(s): (a) $12.90; (b) $7.30; (c) $5.60