1 marble costs $4.
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 24 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 4 - 7
= 40 - 7
= $33
(b)
Number of marbles that do not belong to a set
= 15 ÷ 10
= 1 r 5
Cost of the 5 extra marbles
= 5 x 4
= $20
Cost of 15 marbles
= 33 + 20
= $53
(c)
Number of sets of 10 marbles
= 24 ÷ 10
= 2 r 4
Cost of 20 marbles
= 2 x 33
= $66
Cost of 4 marbles
= 4 x 4
= $16
Cost of 24 marbles
= 66 + 16
= $82
Answer(s): (a) $33; (b) $53; (c) $82