If Adam buys 2 stickers and 3 marbles, it costs $25.30.
If Adam buys 3 stickers and 2 marbles, he will need another $2.90.
- 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 = 25.30 --- (1)
3 stickers + 2 marbles = 25.30 + 2.90 = 28.20 --- (2)
(1) + (2)
5 stickers + 5 marbles = 53.50 --- (3)
(3)
÷ 5 1 sticker + 1 marble = 53.50 ÷ 5 = 10.70 --- (4)
Cost of 1 sticker and 1 marble = $10.70
(b)
3 stickers + 2 marbles = 28.20 --- (2)
(4)
x 2 2 stickers + 2 marbles = 2 x 10.70 = 21.40 --- (5)
(2) - (5)
3 stickers + 2 marbles - 2 stickers - 2 marbles = 28.20 - 21.40
3 stickers - 2 stickers + 2 marbles - 2 marbles = 6.80
1 sticker = 6.80
Cost of 1 sticker = $6.80
(c)
Substitute 1 sticker = 6.80 into (4).
1 sticker + 1 marble = 10.70
6.80 + 1 marble = 10.70
1 marble = 10.70 - 6.80 = 3.90
Cost of 1 marble = $3.90
Answer(s): (a) $10.70; (b) $6.80; (c) $3.90