If Adam buys 4 stickers and 5 marbles, it costs $49.10.
If Adam buys 5 stickers and 4 marbles, he will need another $1.70.
- 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 = 49.10 --- (1)
5 stickers + 4 marbles = 49.10 + 1.70 = 50.80 --- (2)
(1) + (2)
9 stickers + 9 marbles = 99.90 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 99.90 ÷ 9 = 11.10 --- (4)
Cost of 1 sticker and 1 marble = $11.10
(b)
5 stickers + 4 marbles = 50.80 --- (2)
(4)
x 4 4 stickers + 4 marbles = 4 x 11.10 = 44.40 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 50.80 - 44.40
5 stickers - 4 stickers + 4 marbles - 4 marbles = 6.40
1 sticker = 6.40
Cost of 1 sticker = $6.40
(c)
Substitute 1 sticker = 6.40 into (4).
1 sticker + 1 marble = 11.10
6.40 + 1 marble = 11.10
1 marble = 11.10 - 6.40 = 4.70
Cost of 1 marble = $4.70
Answer(s): (a) $11.10; (b) $6.40; (c) $4.70