If Adam buys 4 marbles and 5 stickers, it costs $60.60.
If Adam buys 5 marbles and 4 stickers, he will have $2.40 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 - 2.40 = 58.20 --- (2)
(1) + (2)
9 marbles + 9 stickers = 118.80 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 118.80 ÷ 9 = 13.20 --- (4)
Cost of 1 marble and 1 sticker = $13.20
(b)
(4)
x 4 4 marbles + 4 stickers = 4 x 13.20 = 52.80 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 58.20 - 52.80
5 marbles - 4 marbles - 4 stickers + 4 stickers = 5.40
1 marble = 5.40
Cost of 1 marble = $5.40
(c)
Substitute 1 marble = 5.40 into (4).
1 marble + 1 sticker = 13.20
5.40 + 1 sticker = 13.20
1 sticker = 13.20 - 5.40 = 7.80
Cost of 1 sticker = $7.80
Answer(s): (a) $13.20; (b) $5.40; (c) $7.80