3 stickers and 1 marble cost $13.10.
1 sticker and 3 marbles cost $8.10.
- 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)
3 stickers + 1 marble = 13.10 --- (1)
1 sticker + 3 marbles = 8.10 --- (2)
(1) + (2)
4 stickers + 4 marbles = 13.10 + 8.10
4 stickers + 4 marbles = 21.20 --- (3)
(3)
÷ 44 stickers + 4 marbles = 21.20
1 sticker + 1 marble = 21.20 ÷ 4
1 sticker + 1 marble = 5.30 --- (4)
(b)
(2) - (4)
(1 sticker + 3 marbles) - (1 sticker + 1 marble) = 8.10 - 5.30
1 sticker - 1 sticker + 3 marbles - 1 marble = 2.80
2 marbles = 2.80
1 marble = 2.80 ÷ 2 = 1.40
Cost of 1 marble = $1.40
(c)
Substitute 1 marble = 1.40 into (4).
1 sticker + 1 marble = 5.30
1 sticker + 1.40 = 5.30
1 sticker = 5.30 - 1.40 = 3.90
Cost of 1 sticker = $3.90
(d)
(4)
x 5 1 sticker + 1 marble = 5.30
5 x (1 sticker + 1 marble) = 5 x 5.30
5 stickers + 5 marbles = 26.50
Cost of 5 stickers and 5 marbles = $26.50
Answer(s): (a) $5.30; (b) $1.40; (c) $3.90; (d) $26.50