1 marble costs $8.
For every 10 marbles bought, a discount of $5 is given.
- How much do 10 marbles cost?
- How much do 13 marbles cost?
- How much do 25 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 8 - 5
= 80 - 5
= $75
(b)
Number of marbles that do not belong to a set
= 13 ÷ 10
= 1 r 3
Cost of the 3 extra marbles
= 3 x 8
= $24
Cost of 13 marbles
= 75 + 24
= $99
(c)
Number of sets of 10 marbles
= 25 ÷ 10
= 2 r 5
Cost of 20 marbles
= 2 x 75
= $150
Cost of 5 marbles
= 5 x 8
= $40
Cost of 25 marbles
= 150 + 40
= $190
Answer(s): (a) $75; (b) $99; (c) $190