If Adam buys 3 marbles and 4 stickers, it costs $52.50.
If Adam buys 4 marbles and 3 stickers, he will have $2.80 left.
- Find the cost of 1 marble and 1 sticker.
- Find the cost of 1 marble.
- Find the cost of 1 sticker.
(a)
3 marbles + 4 stickers = 52.50 --- (1)
4 marbles + 3 stickers = 52.50 - 2.80 = 49.70 --- (2)
(1) + (2)
7 marbles + 7 stickers = 102.20 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 102.20 ÷ 7 = 14.60 --- (4)
Cost of 1 marble and 1 sticker = $14.60
(b)
(4)
x 3 3 marbles + 3 stickers = 3 x 14.60 = 43.80 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 49.70 - 43.80
4 marbles - 3 marbles - 3 stickers + 3 stickers = 5.90
1 marble = 5.90
Cost of 1 marble = $5.90
(c)
Substitute 1 marble = 5.90 into (4).
1 marble + 1 sticker = 14.60
5.90 + 1 sticker = 14.60
1 sticker = 14.60 - 5.90 = 8.70
Cost of 1 sticker = $8.70
Answer(s): (a) $14.60; (b) $5.90; (c) $8.70