If Adam buys 5 stickers and 6 marbles, it costs $71.80.
If Adam buys 6 stickers and 5 marbles, he will have $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 = 71.80 --- (1)
6 stickers + 5 marbles = 71.80 - 50 = 66.80 --- (2)
(1) + (2)
11 stickers + 11 marbles = 138.60 --- (3)
(3)
÷ 11 1 sticker + 1 marble = 138.60 ÷ 11 = 12.60 --- (4)
Cost of 1 sticker and 1 marble = $12.60
(b)
(4)
x 5 5 stickers + 5 marbles = 5 x 12.60 = 630 --- (5)
(2) - (5)
6 stickers + 5 marbles - 5 stickers - 5 marbles = 66.80 - 630
6 stickers - 5 stickers - 5 marbles + 5 marbles = 3.80
1 sticker = 3.80
Cost of 1 sticker = $3.80
(c)
Substitute 1 sticker = 3.80 into (4).
1 sticker + 1 marble = 12.60
3.80 + 1 marble = 12.60
1 marble = 12.60 - 3.80 = 8.80
Cost of 1 marble = $8.80
Answer(s): (a) $12.60; (b) $3.80; (c) $8.80