If Adam buys 4 marbles and 5 stickers, it costs $49.30.
If Adam buys 5 marbles and 4 stickers, he will have $7.70 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 = 49.30 --- (1)
5 marbles + 4 stickers = 49.30 - 7.70 = 41.60 --- (2)
(1) + (2)
9 marbles + 9 stickers = 90.90 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 90.90 ÷ 9 = 10.10 --- (4)
Cost of 1 marble and 1 sticker = $10.10
(b)
(4)
x 4 4 marbles + 4 stickers = 4 x 10.10 = 40.40 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 41.60 - 40.40
5 marbles - 4 marbles - 4 stickers + 4 stickers = 1.20
1 marble = 1.20
Cost of 1 marble = $1.20
(c)
Substitute 1 marble = 1.20 into (4).
1 marble + 1 sticker = 10.10
1.20 + 1 sticker = 10.10
1 sticker = 10.10 - 1.20 = 8.90
Cost of 1 sticker = $8.90
Answer(s): (a) $10.10; (b) $1.20; (c) $8.90