2 marbles and 1 sticker cost $4.80.
1 marble and 2 stickers cost $4.50.
- 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 = 4.80 --- (1)
1 marble + 2 stickers = 4.50 --- (2)
(1) + (2)
3 marbles + 3 stickers = 4.80 + 4.50
3 marbles + 3 stickers = 9.30 --- (3)
(3)
÷ 3
3 marbles + 3 stickers = 9.30
1 marble + 1 sticker = 9.30 ÷ 3
1 marble + 1 sticker = 3.10 --- (4)
Cost of 1 marble and 1 sticker = $3.10
(b)
(2) - (4)
(1 marble + 2 stickers) - (1 marble + 1 marble) = 4.50 - 3.10
1 marble - 1 marble + 2 stickers - 1 sticker = 1.40
1 sticker = 1.40
Cost of 1 sticker = $1.40
(c)
Substitute 1 sticker = 1.40 into (4).
1 marble + 1 sticker = 3.10
1 marble + 1.40 = 3.10
1 marble = 3.10 - 1.40 = 1.70
Cost of 1 marble = $1.70
(d)
(4)
x 5 1 marble + 1 sticker = 3.10
5 x (1 marble + 1 marble) = 5 x 3.10
5 marbles + 5 stickers = 15.50
Cost of 5 marbles and 5 stickers = $15.50
Answer(s): (a) $3.10; (b) $1.40; (c) $1.70; (d) $15.50