If Adam buys 3 stickers and 4 marbles, it costs $53.90.
If Adam buys 4 stickers and 3 marbles, he will have $3.50 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 = 53.90 --- (1)
4 stickers + 3 marbles = 53.90 - 3.50 = 50.40 --- (2)
(1) + (2)
7 stickers + 7 marbles = 104.30 --- (3)
(3)
÷ 7 1 sticker + 1 marble = 104.30 ÷ 7 = 14.90 --- (4)
Cost of 1 sticker and 1 marble = $14.90
(b)
(4)
x 3 3 stickers + 3 marbles = 3 x 14.90 = 44.70 --- (5)
(2) - (5)
4 stickers + 3 marbles - 3 stickers - 3 marbles = 50.40 - 44.70
4 stickers - 3 stickers - 3 marbles + 3 marbles = 5.70
1 sticker = 5.70
Cost of 1 sticker = $5.70
(c)
Substitute 1 sticker = 5.70 into (4).
1 sticker + 1 marble = 14.90
5.70 + 1 marble = 14.90
1 marble = 14.90 - 5.70 = 9.20
Cost of 1 marble = $9.20
Answer(s): (a) $14.90; (b) $5.70; (c) $9.20