1 marble costs $8.
For every 10 marbles bought, a discount of $7 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 8 - 7
= 80 - 7
= $73
(b)
Number of marbles that do not belong to a set
= 13 ÷ 10
= 1 r 3
Cost of the 3 extra marbles
= 3 x 8
= $24
Cost of 13 marbles
= 73 + 24
= $97
(c)
Number of sets of 10 marbles
= 22 ÷ 10
= 2 r 2
Cost of 20 marbles
= 2 x 73
= $146
Cost of 2 marbles
= 2 x 8
= $16
Cost of 22 marbles
= 146 + 16
= $162
Answer(s): (a) $73; (b) $97; (c) $162