If Adam buys 5 stickers and 6 marbles, it costs $67.20.
If Adam buys 6 stickers and 5 marbles, he will have $3.50 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 = 67.20 --- (1)
6 stickers + 5 marbles = 67.20 - 3.50 = 63.70 --- (2)
(1) + (2)
11 stickers + 11 marbles = 130.90 --- (3)
(3)
÷ 11 1 sticker + 1 marble = 130.90 ÷ 11 = 11.90 --- (4)
Cost of 1 sticker and 1 marble = $11.90
(b)
(4)
x 5 5 stickers + 5 marbles = 5 x 11.90 = 59.50 --- (5)
(2) - (5)
6 stickers + 5 marbles - 5 stickers - 5 marbles = 63.70 - 59.50
6 stickers - 5 stickers - 5 marbles + 5 marbles = 4.20
1 sticker = 4.20
Cost of 1 sticker = $4.20
(c)
Substitute 1 sticker = 4.20 into (4).
1 sticker + 1 marble = 11.90
4.20 + 1 marble = 11.90
1 marble = 11.90 - 4.20 = 7.70
Cost of 1 marble = $7.70
Answer(s): (a) $11.90; (b) $4.20; (c) $7.70