If Adam buys 4 stickers and 5 marbles, it costs $53.60.
If Adam buys 5 stickers and 4 marbles, he will have $6.40 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 = 53.60 --- (1)
5 stickers + 4 marbles = 53.60 - 6.40 = 47.20 --- (2)
(1) + (2)
9 stickers + 9 marbles = 100.80 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 100.80 ÷ 9 = 11.20 --- (4)
Cost of 1 sticker and 1 marble = $11.20
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 11.20 = 44.80 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 47.20 - 44.80
5 stickers - 4 stickers - 4 marbles + 4 marbles = 2.40
1 sticker = 2.40
Cost of 1 sticker = $2.40
(c)
Substitute 1 sticker = 2.40 into (4).
1 sticker + 1 marble = 11.20
2.40 + 1 marble = 11.20
1 marble = 11.20 - 2.40 = 8.80
Cost of 1 marble = $8.80
Answer(s): (a) $11.20; (b) $2.40; (c) $8.80