1 marble costs $5.
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 23 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 5 - 3
= 50 - 3
= $47
(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
= 47 + 30
= $77
(c)
Number of sets of 10 marbles
= 23 ÷ 10
= 2 r 3
Cost of 20 marbles
= 2 x 47
= $94
Cost of 3 marbles
= 3 x 5
= $15
Cost of 23 marbles
= 94 + 15
= $109
Answer(s): (a) $47; (b) $77; (c) $109