3 marbles and 1 sticker cost $14.30.
1 marble and 3 stickers cost $13.30.
- 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 6 marbles and 6 stickers.
(a)
3 marbles + 1 sticker = 14.30 --- (1)
1 marble + 3 stickers = 13.30 --- (2)
(1) + (2)
4 marbles + 4 stickers = 14.30 + 13.30
4 marbles + 4 stickers = 27.60 --- (3)
(3)
÷ 44 marbles + 4 stickers = 27.60
1 marble + 1 sticker = 27.60 ÷ 4
1 marble + 1 sticker = 6.90 --- (4)
(b)
(2) - (4)
(1 marble + 3 stickers) - (1 marble + 1 marble) = 13.30 - 6.90
1 marble - 1 marble + 3 stickers - 1 sticker = 6.40
2 stickers = 6.40
1 sticker = 6.40 ÷ 2 = 3.20
Cost of 1 sticker = $3.20
(c)
Substitute 1 sticker = 3.20 into (4).
1 marble + 1 sticker = 6.90
1 marble + 3.20 = 6.90
1 marble = 6.90 - 3.20 = 3.70
Cost of 1 marble = $3.70
(d)
(4)
x 6 1 marble + 1 sticker = 6.90
6 x (1 marble + 1 marble) = 6 x 6.90
6 marbles + 6 stickers = 41.40
Cost of 6 marbles and 6 stickers = $41.40
Answer(s): (a) $6.90; (b) $3.20; (c) $3.70; (d) $41.40