1 marble costs $3.
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 26 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 3 - 4
= 30 - 4
= $26
(b)
Number of marbles that do not belong to a set
= 18 ÷ 10
= 1 r 8
Cost of the 8 extra marbles
= 8 x 3
= $24
Cost of 18 marbles
= 26 + 24
= $50
(c)
Number of sets of 10 marbles
= 26 ÷ 10
= 2 r 6
Cost of 20 marbles
= 2 x 26
= $52
Cost of 6 marbles
= 6 x 3
= $18
Cost of 26 marbles
= 52 + 18
= $70
Answer(s): (a) $26; (b) $50; (c) $70