1 marble costs $7.
For every 10 marbles bought, a discount of $5 is given.
- How much do 10 marbles cost?
- How much do 17 marbles cost?
- How much do 32 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 7 - 5
= 70 - 5
= $65
(b)
Number of marbles that do not belong to a set
= 17 ÷ 10
= 1 r 7
Cost of the 7 extra marbles
= 7 x 7
= $49
Cost of 17 marbles
= 65 + 49
= $114
(c)
Number of sets of 10 marbles
= 32 ÷ 10
= 3 r 2
Cost of 30 marbles
= 3 x 65
= $195
Cost of 2 marbles
= 2 x 7
= $14
Cost of 32 marbles
= 195 + 14
= $209
Answer(s): (a) $65; (b) $114; (c) $209