If Adam buys 3 marbles and 4 stickers, it costs $460.
If Adam buys 4 marbles and 3 stickers, he will need another $1.80.
- 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 = 460 --- (1)
4 marbles + 3 stickers = 460 + 1.80 = 47.80 --- (2)
(1) + (2)
7 marbles + 7 stickers = 93.80 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 93.80 ÷ 7 = 13.40 --- (4)
Cost of 1 marble and 1 sticker = $13.40
(b)
4 marbles + 3 stickers = 47.80 --- (2)
(4)
x 3 3 marbles + 3 stickers = 3 x 13.40 = 40.20 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 47.80 - 40.20
4 marbles - 3 marbles + 3 stickers - 3 stickers = 7.60
1 marble = 7.60
Cost of 1 marble = $7.60
(c)
Substitute 1 marble = 7.60 into (4).
1 marble + 1 sticker = 13.40
7.60 + 1 sticker = 13.40
1 sticker = 13.40 - 7.60 = 5.80
Cost of 1 sticker = $5.80
Answer(s): (a) $13.40; (b) $7.60; (c) $5.80