1 marble costs $6.
For every 10 marbles bought, a discount of $7 is given.
- How much do 10 marbles cost?
- How much do 15 marbles cost?
- How much do 22 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 6 - 7
= 60 - 7
= $53
(b)
Number of marbles that do not belong to a set
= 15 ÷ 10
= 1 r 5
Cost of the 5 extra marbles
= 5 x 6
= $30
Cost of 15 marbles
= 53 + 30
= $83
(c)
Number of sets of 10 marbles
= 22 ÷ 10
= 2 r 2
Cost of 20 marbles
= 2 x 53
= $106
Cost of 2 marbles
= 2 x 6
= $12
Cost of 22 marbles
= 106 + 12
= $118
Answer(s): (a) $53; (b) $83; (c) $118