1 marble costs $5.
For every 10 marbles bought, a discount of $5 is given.
- How much do 10 marbles cost?
- How much do 16 marbles cost?
- How much do 24 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
= 16 ÷ 10
= 1 r 6
Cost of the 6 extra marbles
= 6 x 5
= $30
Cost of 16 marbles
= 45 + 30
= $75
(c)
Number of sets of 10 marbles
= 24 ÷ 10
= 2 r 4
Cost of 20 marbles
= 2 x 45
= $90
Cost of 4 marbles
= 4 x 5
= $20
Cost of 24 marbles
= 90 + 20
= $110
Answer(s): (a) $45; (b) $75; (c) $110