2 marbles and 1 sticker cost $9.50.
1 marble and 2 stickers cost $11.80.
- Find the cost of 1 marble and 1 sticker.
- Find the cost of 1 sticker.
- Find the cost of 1 marble.
- Find the cost of 5 marbles and 5 stickers.
(a)
2 marbles + 1 sticker = 9.50 --- (1)
1 marble + 2 stickers = 11.80 --- (2)
(1) + (2)
3 marbles + 3 stickers = 9.50 + 11.80
3 marbles + 3 stickers = 21.30 --- (3)
(3)
÷ 3
3 marbles + 3 stickers = 21.30
1 marble + 1 sticker = 21.30 ÷ 3
1 marble + 1 sticker = 7.10 --- (4)
Cost of 1 marble and 1 sticker = $7.10
(b)
(2) - (4)
(1 marble + 2 stickers) - (1 marble + 1 marble) = 11.80 - 7.10
1 marble - 1 marble + 2 stickers - 1 sticker = 4.70
1 sticker = 4.70
Cost of 1 sticker = $4.70
(c)
Substitute 1 sticker = 4.70 into (4).
1 marble + 1 sticker = 7.10
1 marble + 4.70 = 7.10
1 marble = 7.10 - 4.70 = 2.40
Cost of 1 marble = $2.40
(d)
(4)
x 5 1 marble + 1 sticker = 7.10
5 x (1 marble + 1 marble) = 5 x 7.10
5 marbles + 5 stickers = 35.50
Cost of 5 marbles and 5 stickers = $35.50
Answer(s): (a) $7.10; (b) $4.70; (c) $2.40; (d) $35.50