If Adam buys 4 stickers and 5 marbles, it costs $610.
If Adam buys 5 stickers and 4 marbles, he will need another $3.10.
- 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 = 610 --- (1)
5 stickers + 4 marbles = 610 + 3.10 = 64.10 --- (2)
(1) + (2)
9 stickers + 9 marbles = 125.10 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 125.10 ÷ 9 = 13.90 --- (4)
Cost of 1 sticker and 1 marble = $13.90
(b)
5 stickers + 4 marbles = 64.10 --- (2)
(4)
x 4 4 stickers + 4 marbles = 4 x 13.90 = 55.60 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 64.10 - 55.60
5 stickers - 4 stickers + 4 marbles - 4 marbles = 8.50
1 sticker = 8.50
Cost of 1 sticker = $8.50
(c)
Substitute 1 sticker = 8.50 into (4).
1 sticker + 1 marble = 13.90
8.50 + 1 marble = 13.90
1 marble = 13.90 - 8.50 = 5.40
Cost of 1 marble = $5.40
Answer(s): (a) $13.90; (b) $8.50; (c) $5.40