If Adam buys 4 stickers and 5 marbles, it costs $66.60.
If Adam buys 5 stickers and 4 marbles, he will have $2.70 left.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
(a)
4 stickers + 5 marbles = 66.60 --- (1)
5 stickers + 4 marbles = 66.60 - 2.70 = 63.90 --- (2)
(1) + (2)
9 stickers + 9 marbles = 130.50 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 130.50 ÷ 9 = 14.50 --- (4)
Cost of 1 sticker and 1 marble = $14.50
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 14.50 = 580 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 63.90 - 580
5 stickers - 4 stickers - 4 marbles + 4 marbles = 5.90
1 sticker = 5.90
Cost of 1 sticker = $5.90
(c)
Substitute 1 sticker = 5.90 into (4).
1 sticker + 1 marble = 14.50
5.90 + 1 marble = 14.50
1 marble = 14.50 - 5.90 = 8.60
Cost of 1 marble = $8.60
Answer(s): (a) $14.50; (b) $5.90; (c) $8.60