1 marble costs $6.
For every 10 marbles bought, a discount of $4 is given.
- How much do 10 marbles cost?
- How much do 18 marbles cost?
- How much do 23 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 6 - 4
= 60 - 4
= $56
(b)
Number of marbles that do not belong to a set
= 18 ÷ 10
= 1 r 8
Cost of the 8 extra marbles
= 8 x 6
= $48
Cost of 18 marbles
= 56 + 48
= $104
(c)
Number of sets of 10 marbles
= 23 ÷ 10
= 2 r 3
Cost of 20 marbles
= 2 x 56
= $112
Cost of 3 marbles
= 3 x 6
= $18
Cost of 23 marbles
= 112 + 18
= $130
Answer(s): (a) $56; (b) $104; (c) $130