3 marbles and 1 sticker cost $15.30.
1 marble and 3 stickers cost $9.90.
- 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)
3 marbles + 1 sticker = 15.30 --- (1)
1 marble + 3 stickers = 9.90 --- (2)
(1) + (2)
4 marbles + 4 stickers = 15.30 + 9.90
4 marbles + 4 stickers = 25.20 --- (3)
(3)
÷ 44 marbles + 4 stickers = 25.20
1 marble + 1 sticker = 25.20 ÷ 4
1 marble + 1 sticker = 6.30 --- (4)
(b)
(2) - (4)
(1 marble + 3 stickers) - (1 marble + 1 marble) = 9.90 - 6.30
1 marble - 1 marble + 3 stickers - 1 sticker = 3.60
2 stickers = 3.60
1 sticker = 3.60 ÷ 2 = 1.80
Cost of 1 sticker = $1.80
(c)
Substitute 1 sticker = 1.80 into (4).
1 marble + 1 sticker = 6.30
1 marble + 1.80 = 6.30
1 marble = 6.30 - 1.80 = 4.50
Cost of 1 marble = $4.50
(d)
(4)
x 5 1 marble + 1 sticker = 6.30
5 x (1 marble + 1 marble) = 5 x 6.30
5 marbles + 5 stickers = 31.50
Cost of 5 marbles and 5 stickers = $31.50
Answer(s): (a) $6.30; (b) $1.80; (c) $4.50; (d) $31.50