If Adam buys 2 stickers and 3 marbles, it costs $29.80.
If Adam buys 3 stickers and 2 marbles, he will need another $3.90.
- 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 = 29.80 --- (1)
3 stickers + 2 marbles = 29.80 + 3.90 = 33.70 --- (2)
(1) + (2)
5 stickers + 5 marbles = 63.50 --- (3)
(3)
÷ 5 1 sticker + 1 marble = 63.50 ÷ 5 = 12.70 --- (4)
Cost of 1 sticker and 1 marble = $12.70
(b)
3 stickers + 2 marbles = 33.70 --- (2)
(4)
x 2 2 stickers + 2 marbles = 2 x 12.70 = 25.40 --- (5)
(2) - (5)
3 stickers + 2 marbles - 2 stickers - 2 marbles = 33.70 - 25.40
3 stickers - 2 stickers + 2 marbles - 2 marbles = 8.30
1 sticker = 8.30
Cost of 1 sticker = $8.30
(c)
Substitute 1 sticker = 8.30 into (4).
1 sticker + 1 marble = 12.70
8.30 + 1 marble = 12.70
1 marble = 12.70 - 8.30 = 4.40
Cost of 1 marble = $4.40
Answer(s): (a) $12.70; (b) $8.30; (c) $4.40