If Adam buys 3 marbles and 4 stickers, it costs $41.70.
If Adam buys 4 marbles and 3 stickers, he will have $2.20 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 = 41.70 --- (1)
4 marbles + 3 stickers = 41.70 - 2.20 = 39.50 --- (2)
(1) + (2)
7 marbles + 7 stickers = 81.20 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 81.20 ÷ 7 = 11.60 --- (4)
Cost of 1 marble and 1 sticker = $11.60
(b)
(4)
x 3 3 marbles + 3 stickers = 3 x 11.60 = 34.80 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 39.50 - 34.80
4 marbles - 3 marbles - 3 stickers + 3 stickers = 4.70
1 marble = 4.70
Cost of 1 marble = $4.70
(c)
Substitute 1 marble = 4.70 into (4).
1 marble + 1 sticker = 11.60
4.70 + 1 sticker = 11.60
1 sticker = 11.60 - 4.70 = 6.90
Cost of 1 sticker = $6.90
Answer(s): (a) $11.60; (b) $4.70; (c) $6.90