1 marble costs $3.
For every 10 marbles bought, a discount of $4 is given.
- How much do 10 marbles cost?
- How much do 17 marbles cost?
- How much do 24 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 3 - 4
= 30 - 4
= $26
(b)
Number of marbles that do not belong to a set
= 17 ÷ 10
= 1 r 7
Cost of the 7 extra marbles
= 7 x 3
= $21
Cost of 17 marbles
= 26 + 21
= $47
(c)
Number of sets of 10 marbles
= 24 ÷ 10
= 2 r 4
Cost of 20 marbles
= 2 x 26
= $52
Cost of 4 marbles
= 4 x 3
= $12
Cost of 24 marbles
= 52 + 12
= $64
Answer(s): (a) $26; (b) $47; (c) $64