1 marble costs $5.
For every 10 marbles bought, a discount of $5 is given.
- How much do 10 marbles cost?
- How much do 12 marbles cost?
- How much do 36 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 5 - 5
= 50 - 5
= $45
(b)
Number of marbles that do not belong to a set
= 12 ÷ 10
= 1 r 2
Cost of the 2 extra marbles
= 2 x 5
= $10
Cost of 12 marbles
= 45 + 10
= $55
(c)
Number of sets of 10 marbles
= 36 ÷ 10
= 3 r 6
Cost of 30 marbles
= 3 x 45
= $135
Cost of 6 marbles
= 6 x 5
= $30
Cost of 36 marbles
= 135 + 30
= $165
Answer(s): (a) $45; (b) $55; (c) $165