If Adam buys 3 stickers and 4 marbles, it costs $39.60.
If Adam buys 4 stickers and 3 marbles, he will need another $5.50.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
(a)
3 stickers + 4 marbles = 39.60 --- (1)
4 stickers + 3 marbles = 39.60 + 5.50 = 45.10 --- (2)
(1) + (2)
7 stickers + 7 marbles = 84.70 --- (3)
(3)
÷ 7 1 sticker + 1 marble = 84.70 ÷ 7 = 12.10 --- (4)
Cost of 1 sticker and 1 marble = $12.10
(b)
4 stickers + 3 marbles = 45.10 --- (2)
(4)
x 3 3 stickers + 3 marbles = 3 x 12.10 = 36.30 --- (5)
(2) - (5)
4 stickers + 3 marbles - 3 stickers - 3 marbles = 45.10 - 36.30
4 stickers - 3 stickers + 3 marbles - 3 marbles = 8.80
1 sticker = 8.80
Cost of 1 sticker = $8.80
(c)
Substitute 1 sticker = 8.80 into (4).
1 sticker + 1 marble = 12.10
8.80 + 1 marble = 12.10
1 marble = 12.10 - 8.80 = 3.30
Cost of 1 marble = $3.30
Answer(s): (a) $12.10; (b) $8.80; (c) $3.30