If Adam buys 5 stickers and 6 marbles, it costs $75.20.
If Adam buys 6 stickers and 5 marbles, he will have $1.90 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 = 75.20 --- (1)
6 stickers + 5 marbles = 75.20 - 1.90 = 73.30 --- (2)
(1) + (2)
11 stickers + 11 marbles = 148.50 --- (3)
(3)
÷ 11 1 sticker + 1 marble = 148.50 ÷ 11 = 13.50 --- (4)
Cost of 1 sticker and 1 marble = $13.50
(b)
(4)
x 5 5 stickers + 5 marbles = 5 x 13.50 = 67.50 --- (5)
(2) - (5)
6 stickers + 5 marbles - 5 stickers - 5 marbles = 73.30 - 67.50
6 stickers - 5 stickers - 5 marbles + 5 marbles = 5.80
1 sticker = 5.80
Cost of 1 sticker = $5.80
(c)
Substitute 1 sticker = 5.80 into (4).
1 sticker + 1 marble = 13.50
5.80 + 1 marble = 13.50
1 marble = 13.50 - 5.80 = 7.70
Cost of 1 marble = $7.70
Answer(s): (a) $13.50; (b) $5.80; (c) $7.70