1 marble costs $5.
For every 10 marbles bought, a discount of $7 is given.
- How much do 10 marbles cost?
- How much do 18 marbles cost?
- How much do 26 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 5 - 7
= 50 - 7
= $43
(b)
Number of marbles that do not belong to a set
= 18 ÷ 10
= 1 r 8
Cost of the 8 extra marbles
= 8 x 5
= $40
Cost of 18 marbles
= 43 + 40
= $83
(c)
Number of sets of 10 marbles
= 26 ÷ 10
= 2 r 6
Cost of 20 marbles
= 2 x 43
= $86
Cost of 6 marbles
= 6 x 5
= $30
Cost of 26 marbles
= 86 + 30
= $116
Answer(s): (a) $43; (b) $83; (c) $116