2 marbles and 1 sticker cost $5.30.
1 marble and 2 stickers cost $6.10.
- 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 4 marbles and 4 stickers.
(a)
2 marbles + 1 sticker = 5.30 --- (1)
1 marble + 2 stickers = 6.10 --- (2)
(1) + (2)
3 marbles + 3 stickers = 5.30 + 6.10
3 marbles + 3 stickers = 11.40 --- (3)
(3)
÷ 3
3 marbles + 3 stickers = 11.40
1 marble + 1 sticker = 11.40 ÷ 3
1 marble + 1 sticker = 3.80 --- (4)
Cost of 1 marble and 1 sticker = $3.80
(b)
(2) - (4)
(1 marble + 2 stickers) - (1 marble + 1 marble) = 6.10 - 3.80
1 marble - 1 marble + 2 stickers - 1 sticker = 2.30
1 sticker = 2.30
Cost of 1 sticker = $2.30
(c)
Substitute 1 sticker = 2.30 into (4).
1 marble + 1 sticker = 3.80
1 marble + 2.30 = 3.80
1 marble = 3.80 - 2.30 = 1.50
Cost of 1 marble = $1.50
(d)
(4)
x 4 1 marble + 1 sticker = 3.80
4 x (1 marble + 1 marble) = 4 x 3.80
4 marbles + 4 stickers = 15.20
Cost of 4 marbles and 4 stickers = $15.20
Answer(s): (a) $3.80; (b) $2.30; (c) $1.50; (d) $15.20