If Adam buys 3 stickers and 4 marbles, it costs $44.50.
If Adam buys 4 stickers and 3 marbles, he will need another $3.40.
- 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 = 44.50 --- (1)
4 stickers + 3 marbles = 44.50 + 3.40 = 47.90 --- (2)
(1) + (2)
7 stickers + 7 marbles = 92.40 --- (3)
(3)
÷ 7 1 sticker + 1 marble = 92.40 ÷ 7 = 13.20 --- (4)
Cost of 1 sticker and 1 marble = $13.20
(b)
4 stickers + 3 marbles = 47.90 --- (2)
(4)
x 3 3 stickers + 3 marbles = 3 x 13.20 = 39.60 --- (5)
(2) - (5)
4 stickers + 3 marbles - 3 stickers - 3 marbles = 47.90 - 39.60
4 stickers - 3 stickers + 3 marbles - 3 marbles = 8.30
1 sticker = 8.30
Cost of 1 sticker = $8.30
(c)
Substitute 1 sticker = 8.30 into (4).
1 sticker + 1 marble = 13.20
8.30 + 1 marble = 13.20
1 marble = 13.20 - 8.30 = 4.90
Cost of 1 marble = $4.90
Answer(s): (a) $13.20; (b) $8.30; (c) $4.90