1 marble costs $4.
For every 10 marbles bought, a discount of $3 is given.
- How much do 10 marbles cost?
- How much do 16 marbles cost?
- How much do 23 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 4 - 3
= 40 - 3
= $37
(b)
Number of marbles that do not belong to a set
= 16 ÷ 10
= 1 r 6
Cost of the 6 extra marbles
= 6 x 4
= $24
Cost of 16 marbles
= 37 + 24
= $61
(c)
Number of sets of 10 marbles
= 23 ÷ 10
= 2 r 3
Cost of 20 marbles
= 2 x 37
= $74
Cost of 3 marbles
= 3 x 4
= $12
Cost of 23 marbles
= 74 + 12
= $86
Answer(s): (a) $37; (b) $61; (c) $86