If Adam buys 4 stickers and 5 marbles, it costs $64.70.
If Adam buys 5 stickers and 4 marbles, he will have $6.10 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 = 64.70 --- (1)
5 stickers + 4 marbles = 64.70 - 6.10 = 58.60 --- (2)
(1) + (2)
9 stickers + 9 marbles = 123.30 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 123.30 ÷ 9 = 13.70 --- (4)
Cost of 1 sticker and 1 marble = $13.70
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 13.70 = 54.80 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 58.60 - 54.80
5 stickers - 4 stickers - 4 marbles + 4 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 = 13.70
3.80 + 1 marble = 13.70
1 marble = 13.70 - 3.80 = 9.90
Cost of 1 marble = $9.90
Answer(s): (a) $13.70; (b) $3.80; (c) $9.90