2 marbles and 1 sticker cost $8.50.
1 marble and 2 stickers cost $11.60.
- 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 = 8.50 --- (1)
1 marble + 2 stickers = 11.60 --- (2)
(1) + (2)
3 marbles + 3 stickers = 8.50 + 11.60
3 marbles + 3 stickers = 20.10 --- (3)
(3)
÷ 3
3 marbles + 3 stickers = 20.10
1 marble + 1 sticker = 20.10 ÷ 3
1 marble + 1 sticker = 6.70 --- (4)
Cost of 1 marble and 1 sticker = $6.70
(b)
(2) - (4)
(1 marble + 2 stickers) - (1 marble + 1 marble) = 11.60 - 6.70
1 marble - 1 marble + 2 stickers - 1 sticker = 4.90
1 sticker = 4.90
Cost of 1 sticker = $4.90
(c)
Substitute 1 sticker = 4.90 into (4).
1 marble + 1 sticker = 6.70
1 marble + 4.90 = 6.70
1 marble = 6.70 - 4.90 = 1.80
Cost of 1 marble = $1.80
(d)
(4)
x 5 1 marble + 1 sticker = 6.70
5 x (1 marble + 1 marble) = 5 x 6.70
5 marbles + 5 stickers = 33.50
Cost of 5 marbles and 5 stickers = $33.50
Answer(s): (a) $6.70; (b) $4.90; (c) $1.80; (d) $33.50