If Adam buys 4 stickers and 5 marbles, it costs $45.20.
If Adam buys 5 stickers and 4 marbles, he will have $4.90 left.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
(a)
4 stickers + 5 marbles = 45.20 --- (1)
5 stickers + 4 marbles = 45.20 - 4.90 = 40.30 --- (2)
(1) + (2)
9 stickers + 9 marbles = 85.50 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 85.50 ÷ 9 = 9.50 --- (4)
Cost of 1 sticker and 1 marble = $9.50
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 9.50 = 380 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 40.30 - 380
5 stickers - 4 stickers - 4 marbles + 4 marbles = 2.30
1 sticker = 2.30
Cost of 1 sticker = $2.30
(c)
Substitute 1 sticker = 2.30 into (4).
1 sticker + 1 marble = 9.50
2.30 + 1 marble = 9.50
1 marble = 9.50 - 2.30 = 7.20
Cost of 1 marble = $7.20
Answer(s): (a) $9.50; (b) $2.30; (c) $7.20