2 stickers and 1 marble cost $4.40.
1 sticker and 2 marbles cost $4.90.
- Find the cost of 1 sticker and 1 marble.
- Find the cost of 1 marble.
- Find the cost of 1 sticker.
- Find the cost of 5 stickers and 5 marbles.
(a)
2 stickers + 1 marble = 4.40 --- (1)
1 sticker + 2 marbles = 4.90 --- (2)
(1) + (2)
3 stickers + 3 marbles = 4.40 + 4.90
3 stickers + 3 marbles = 9.30 --- (3)
(3)
÷ 3
3 stickers + 3 marbles = 9.30
1 sticker + 1 marble = 9.30 ÷ 3
1 sticker + 1 marble = 3.10 --- (4)
Cost of 1 sticker and 1 marble = $3.10
(b)
(2) - (4)
(1 sticker + 2 marbles) - (1 sticker + 1 marble) = 4.90 - 3.10
1 sticker - 1 sticker + 2 marbles - 1 marble = 1.80
1 marble = 1.80
Cost of 1 marble = $1.80
(c)
Substitute 1 marble = 1.80 into (4).
1 sticker + 1 marble = 3.10
1 sticker + 1.80 = 3.10
1 sticker = 3.10 - 1.80 = 1.30
Cost of 1 sticker = $1.30
(d)
(4)
x 5 1 sticker + 1 marble = 3.10
5 x (1 sticker + 1 marble) = 5 x 3.10
5 stickers + 5 marbles = 15.50
Cost of 5 stickers and 5 marbles = $15.50
Answer(s): (a) $3.10; (b) $1.80; (c) $1.30; (d) $15.50