If Adam buys 4 stickers and 5 marbles, it costs $49.90.
If Adam buys 5 stickers and 4 marbles, he will have $5.30 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 = 49.90 --- (1)
5 stickers + 4 marbles = 49.90 - 5.30 = 44.60 --- (2)
(1) + (2)
9 stickers + 9 marbles = 94.50 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 94.50 ÷ 9 = 10.50 --- (4)
Cost of 1 sticker and 1 marble = $10.50
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 10.50 = 420 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 44.60 - 420
5 stickers - 4 stickers - 4 marbles + 4 marbles = 2.60
1 sticker = 2.60
Cost of 1 sticker = $2.60
(c)
Substitute 1 sticker = 2.60 into (4).
1 sticker + 1 marble = 10.50
2.60 + 1 marble = 10.50
1 marble = 10.50 - 2.60 = 7.90
Cost of 1 marble = $7.90
Answer(s): (a) $10.50; (b) $2.60; (c) $7.90