If Adam buys 3 marbles and 4 stickers, it costs $42.30.
If Adam buys 4 marbles and 3 stickers, he will have $6.20 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 = 42.30 --- (1)
4 marbles + 3 stickers = 42.30 - 6.20 = 36.10 --- (2)
(1) + (2)
7 marbles + 7 stickers = 78.40 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 78.40 ÷ 7 = 11.20 --- (4)
Cost of 1 marble and 1 sticker = $11.20
(b)
(4)
x 3 3 marbles + 3 stickers = 3 x 11.20 = 33.60 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 36.10 - 33.60
4 marbles - 3 marbles - 3 stickers + 3 stickers = 2.50
1 marble = 2.50
Cost of 1 marble = $2.50
(c)
Substitute 1 marble = 2.50 into (4).
1 marble + 1 sticker = 11.20
2.50 + 1 sticker = 11.20
1 sticker = 11.20 - 2.50 = 8.70
Cost of 1 sticker = $8.70
Answer(s): (a) $11.20; (b) $2.50; (c) $8.70