If Adam buys 5 stickers and 6 marbles, it costs $54.90.
If Adam buys 6 stickers and 5 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)
5 stickers + 6 marbles = 54.90 --- (1)
6 stickers + 5 marbles = 54.90 - 6.40 = 48.50 --- (2)
(1) + (2)
11 stickers + 11 marbles = 103.40 --- (3)
(3)
÷ 11 1 sticker + 1 marble = 103.40 ÷ 11 = 9.40 --- (4)
Cost of 1 sticker and 1 marble = $9.40
(b)
(4)
x 5 5 stickers + 5 marbles = 5 x 9.40 = 470 --- (5)
(2) - (5)
6 stickers + 5 marbles - 5 stickers - 5 marbles = 48.50 - 470
6 stickers - 5 stickers - 5 marbles + 5 marbles = 1.50
1 sticker = 1.50
Cost of 1 sticker = $1.50
(c)
Substitute 1 sticker = 1.50 into (4).
1 sticker + 1 marble = 9.40
1.50 + 1 marble = 9.40
1 marble = 9.40 - 1.50 = 7.90
Cost of 1 marble = $7.90
Answer(s): (a) $9.40; (b) $1.50; (c) $7.90