If Adam buys 4 stickers and 5 marbles, it costs $55.90.
If Adam buys 5 stickers and 4 marbles, he will have $5.60 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 = 55.90 --- (1)
5 stickers + 4 marbles = 55.90 - 5.60 = 50.30 --- (2)
(1) + (2)
9 stickers + 9 marbles = 106.20 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 106.20 ÷ 9 = 11.80 --- (4)
Cost of 1 sticker and 1 marble = $11.80
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 11.80 = 47.20 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 50.30 - 47.20
5 stickers - 4 stickers - 4 marbles + 4 marbles = 3.10
1 sticker = 3.10
Cost of 1 sticker = $3.10
(c)
Substitute 1 sticker = 3.10 into (4).
1 sticker + 1 marble = 11.80
3.10 + 1 marble = 11.80
1 marble = 11.80 - 3.10 = 8.70
Cost of 1 marble = $8.70
Answer(s): (a) $11.80; (b) $3.10; (c) $8.70