If Adam buys 5 stickers and 6 marbles, it costs $57.60.
If Adam buys 6 stickers and 5 marbles, he will have $6.30 left.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
(a)
5 stickers + 6 marbles = 57.60 --- (1)
6 stickers + 5 marbles = 57.60 - 6.30 = 51.30 --- (2)
(1) + (2)
11 stickers + 11 marbles = 108.90 --- (3)
(3)
÷ 11 1 sticker + 1 marble = 108.90 ÷ 11 = 9.90 --- (4)
Cost of 1 sticker and 1 marble = $9.90
(b)
(4)
x 5 5 stickers + 5 marbles = 5 x 9.90 = 49.50 --- (5)
(2) - (5)
6 stickers + 5 marbles - 5 stickers - 5 marbles = 51.30 - 49.50
6 stickers - 5 stickers - 5 marbles + 5 marbles = 1.80
1 sticker = 1.80
Cost of 1 sticker = $1.80
(c)
Substitute 1 sticker = 1.80 into (4).
1 sticker + 1 marble = 9.90
1.80 + 1 marble = 9.90
1 marble = 9.90 - 1.80 = 8.10
Cost of 1 marble = $8.10
Answer(s): (a) $9.90; (b) $1.80; (c) $8.10