If Adam buys 4 marbles and 5 stickers, it costs $67.30.
If Adam buys 5 marbles and 4 stickers, he will have $4.10 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 = 67.30 --- (1)
5 marbles + 4 stickers = 67.30 - 4.10 = 63.20 --- (2)
(1) + (2)
9 marbles + 9 stickers = 130.50 --- (3)
(3)
÷ 9 1 marble + 1 sticker = 130.50 ÷ 9 = 14.50 --- (4)
Cost of 1 marble and 1 sticker = $14.50
(b)
(4)
x 4 4 marbles + 4 stickers = 4 x 14.50 = 580 --- (5)
(2) - (5)
5 marbles + 4 stickers - 4 marbles - 4 stickers = 63.20 - 580
5 marbles - 4 marbles - 4 stickers + 4 stickers = 5.20
1 marble = 5.20
Cost of 1 marble = $5.20
(c)
Substitute 1 marble = 5.20 into (4).
1 marble + 1 sticker = 14.50
5.20 + 1 sticker = 14.50
1 sticker = 14.50 - 5.20 = 9.30
Cost of 1 sticker = $9.30
Answer(s): (a) $14.50; (b) $5.20; (c) $9.30