1 marble costs $9.
For every 10 marbles bought, a discount of $4 is given.
- How much do 10 marbles cost?
- How much do 13 marbles cost?
- How much do 26 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 9 - 4
= 90 - 4
= $86
(b)
Number of marbles that do not belong to a set
= 13 ÷ 10
= 1 r 3
Cost of the 3 extra marbles
= 3 x 9
= $27
Cost of 13 marbles
= 86 + 27
= $113
(c)
Number of sets of 10 marbles
= 26 ÷ 10
= 2 r 6
Cost of 20 marbles
= 2 x 86
= $172
Cost of 6 marbles
= 6 x 9
= $54
Cost of 26 marbles
= 172 + 54
= $226
Answer(s): (a) $86; (b) $113; (c) $226