If Adam buys 3 stickers and 4 marbles, it costs $43.50.
If Adam buys 4 stickers and 3 marbles, he will have $7.90 left.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
(a)
3 stickers + 4 marbles = 43.50 --- (1)
4 stickers + 3 marbles = 43.50 - 7.90 = 35.60 --- (2)
(1) + (2)
7 stickers + 7 marbles = 79.10 --- (3)
(3)
÷ 7 1 sticker + 1 marble = 79.10 ÷ 7 = 11.30 --- (4)
Cost of 1 sticker and 1 marble = $11.30
(b)
(4)
x 3 3 stickers + 3 marbles = 3 x 11.30 = 33.90 --- (5)
(2) - (5)
4 stickers + 3 marbles - 3 stickers - 3 marbles = 35.60 - 33.90
4 stickers - 3 stickers - 3 marbles + 3 marbles = 1.70
1 sticker = 1.70
Cost of 1 sticker = $1.70
(c)
Substitute 1 sticker = 1.70 into (4).
1 sticker + 1 marble = 11.30
1.70 + 1 marble = 11.30
1 marble = 11.30 - 1.70 = 9.60
Cost of 1 marble = $9.60
Answer(s): (a) $11.30; (b) $1.70; (c) $9.60