1 marble costs $4.
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 27 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 4 - 5
= 40 - 5
= $35
(b)
Number of marbles that do not belong to a set
= 13 ÷ 10
= 1 r 3
Cost of the 3 extra marbles
= 3 x 4
= $12
Cost of 13 marbles
= 35 + 12
= $47
(c)
Number of sets of 10 marbles
= 27 ÷ 10
= 2 r 7
Cost of 20 marbles
= 2 x 35
= $70
Cost of 7 marbles
= 7 x 4
= $28
Cost of 27 marbles
= 70 + 28
= $98
Answer(s): (a) $35; (b) $47; (c) $98