1 marble costs $8.
For every 10 marbles bought, a discount of $7 is given.
- How much do 10 marbles cost?
- How much do 16 marbles cost?
- How much do 25 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 8 - 7
= 80 - 7
= $73
(b)
Number of marbles that do not belong to a set
= 16 ÷ 10
= 1 r 6
Cost of the 6 extra marbles
= 6 x 8
= $48
Cost of 16 marbles
= 73 + 48
= $121
(c)
Number of sets of 10 marbles
= 25 ÷ 10
= 2 r 5
Cost of 20 marbles
= 2 x 73
= $146
Cost of 5 marbles
= 5 x 8
= $40
Cost of 25 marbles
= 146 + 40
= $186
Answer(s): (a) $73; (b) $121; (c) $186