If Adam buys 4 marbles and 5 stickers, it costs $60.60.
If Adam buys 5 marbles and 4 stickers, he will have $6.90 left.
- Find the cost of 1 marble and 1 sticker.
- Find the cost of 1 marble.
- Find the cost of 1 sticker.
(a)
4 marbles + 5 stickers = 60.60 --- (1)
5 marbles + 4 stickers = 60.60 - 6.90 = 53.70 --- (2)
(1) + (2)
9 marbles + 9 stickers = 114.30 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 114.30 ÷ 9 = 12.70 --- (4)
Cost of 1 marble and 1 sticker = $12.70
(b)
(4)
x 4 4 marbles + 4 stickers = 4 x 12.70 = 50.80 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 53.70 - 50.80
5 marbles - 4 marbles - 4 stickers + 4 stickers = 2.90
1 marble = 2.90
Cost of 1 marble = $2.90
(c)
Substitute 1 marble = 2.90 into (4).
1 marble + 1 sticker = 12.70
2.90 + 1 sticker = 12.70
1 sticker = 12.70 - 2.90 = 9.80
Cost of 1 sticker = $9.80
Answer(s): (a) $12.70; (b) $2.90; (c) $9.80