If Adam buys 4 stickers and 5 marbles, it costs $47.70.
If Adam buys 5 stickers and 4 marbles, he will have $3.60 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 = 47.70 --- (1)
5 stickers + 4 marbles = 47.70 - 3.60 = 44.10 --- (2)
(1) + (2)
9 stickers + 9 marbles = 91.80 --- (3)
(3)
÷ 9 1 sticker + 1 marble = 91.80 ÷ 9 = 10.20 --- (4)
Cost of 1 sticker and 1 marble = $10.20
(b)
(4)
x 4 4 stickers + 4 marbles = 4 x 10.20 = 40.80 --- (5)
(2) - (5)
5 stickers + 4 marbles - 4 stickers - 4 marbles = 44.10 - 40.80
5 stickers - 4 stickers - 4 marbles + 4 marbles = 3.30
1 sticker = 3.30
Cost of 1 sticker = $3.30
(c)
Substitute 1 sticker = 3.30 into (4).
1 sticker + 1 marble = 10.20
3.30 + 1 marble = 10.20
1 marble = 10.20 - 3.30 = 6.90
Cost of 1 marble = $6.90
Answer(s): (a) $10.20; (b) $3.30; (c) $6.90