If Adam buys 4 stickers and 5 marbles, it costs $46.70.
If Adam buys 5 stickers and 4 marbles, he will have $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 = 46.70 --- (1)
5 stickers + 4 marbles = 46.70 - 70 = 39.70 --- (2)
(1) + (2)
9 stickers + 9 marbles = 86.40 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 86.40 ÷ 9 = 9.60 --- (4)
Cost of 1 sticker and 1 marble = $9.60
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 9.60 = 38.40 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 39.70 - 38.40
5 stickers - 4 stickers - 4 marbles + 4 marbles = 1.30
1 sticker = 1.30
Cost of 1 sticker = $1.30
(c)
Substitute 1 sticker = 1.30 into (4).
1 sticker + 1 marble = 9.60
1.30 + 1 marble = 9.60
1 marble = 9.60 - 1.30 = 8.30
Cost of 1 marble = $8.30
Answer(s): (a) $9.60; (b) $1.30; (c) $8.30