1 marble costs $6.
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 39 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 6 - 3
= 60 - 3
= $57
(b)
Number of marbles that do not belong to a set
= 16 ÷ 10
= 1 r 6
Cost of the 6 extra marbles
= 6 x 6
= $36
Cost of 16 marbles
= 57 + 36
= $93
(c)
Number of sets of 10 marbles
= 39 ÷ 10
= 3 r 9
Cost of 30 marbles
= 3 x 57
= $171
Cost of 9 marbles
= 9 x 6
= $54
Cost of 39 marbles
= 171 + 54
= $225
Answer(s): (a) $57; (b) $93; (c) $225