Adam spends $16.90 on 3 marbles and 4 stickers.
A marble costs 3 times as much as 1 sticker.
- How much does 1 marble cost?
- How much do 5 marbles cost?
- How much do a sticker and 5 marbles cost?
- How much does 1 sticker cost less than 5 marbles?
(a)
Let the cheaper item be 1 u.
Cost of 1 sticker = 1 u
Cost of 1 marble = 3 u
Cost of 3 marbles = 3 x 3 u = 9 u
Cost of 4 stickers = 4 x 1 u = 4 u
Total cost of 3 marbles and 4 stickers
= 9 u + 4 u
= 13 u
13 u = 16.90
1 u = 16.90 ÷ 13 = 1.30
Cost of 1 marble
= 3 u
= 3 x 1.30
= $3.90
(b)
Cost of 5 marbles
= 5 x 3.90
= $19.50
(c)
Cost of 1 sticker and 5 marbles
= 1.30 + 19.50
= $20.80
(d)
Cost of 1 sticker less than 5 marbles
= 19.50 - 1.30
= $18.20
Answer(s): (a) $3.90; (b) $19.50; (c) $20.80; (d) $18.20