1 marble costs $6.
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 22 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 6 - 5
= 60 - 5
= $55
(b)
Number of marbles that do not belong to a set
= 13 ÷ 10
= 1 r 3
Cost of the 3 extra marbles
= 3 x 6
= $18
Cost of 13 marbles
= 55 + 18
= $73
(c)
Number of sets of 10 marbles
= 22 ÷ 10
= 2 r 2
Cost of 20 marbles
= 2 x 55
= $110
Cost of 2 marbles
= 2 x 6
= $12
Cost of 22 marbles
= 110 + 12
= $122
Answer(s): (a) $55; (b) $73; (c) $122