If Adam buys 3 marbles and 4 stickers, it costs $440.
If Adam buys 4 marbles and 3 stickers, he will need another $3.70.
- 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 = 440 --- (1)
4 marbles + 3 stickers = 440 + 3.70 = 47.70 --- (2)
(1) + (2)
7 marbles + 7 stickers = 91.70 --- (3)
(3)
÷ 7 1 marble + 1 sticker = 91.70 ÷ 7 = 13.10 --- (4)
Cost of 1 marble and 1 sticker = $13.10
(b)
4 marbles + 3 stickers = 47.70 --- (2)
(4)
x 3 3 marbles + 3 stickers = 3 x 13.10 = 39.30 --- (5)
(2) - (5)
4 marbles + 3 stickers - 3 marbles - 3 stickers = 47.70 - 39.30
4 marbles - 3 marbles + 3 stickers - 3 stickers = 8.40
1 marble = 8.40
Cost of 1 marble = $8.40
(c)
Substitute 1 marble = 8.40 into (4).
1 marble + 1 sticker = 13.10
8.40 + 1 sticker = 13.10
1 sticker = 13.10 - 8.40 = 4.70
Cost of 1 sticker = $4.70
Answer(s): (a) $13.10; (b) $8.40; (c) $4.70