If Adam buys 4 stickers and 5 marbles, it costs $54.70.
If Adam buys 5 stickers and 4 marbles, he will have $5.90 left.
- 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 = 54.70 --- (1)
5 stickers + 4 marbles = 54.70 - 5.90 = 48.80 --- (2)
(1) + (2)
9 stickers + 9 marbles = 103.50 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 103.50 ÷ 9 = 11.50 --- (4)
Cost of 1 sticker and 1 marble = $11.50
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 11.50 = 460 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 48.80 - 460
5 stickers - 4 stickers - 4 marbles + 4 marbles = 2.80
1 sticker = 2.80
Cost of 1 sticker = $2.80
(c)
Substitute 1 sticker = 2.80 into (4).
1 sticker + 1 marble = 11.50
2.80 + 1 marble = 11.50
1 marble = 11.50 - 2.80 = 8.70
Cost of 1 marble = $8.70
Answer(s): (a) $11.50; (b) $2.80; (c) $8.70