1 marble costs $5.
For every 10 marbles bought, a discount of $3 is given.
- How much do 10 marbles cost?
- How much do 17 marbles cost?
- How much do 28 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 5 - 3
= 50 - 3
= $47
(b)
Number of marbles that do not belong to a set
= 17 ÷ 10
= 1 r 7
Cost of the 7 extra marbles
= 7 x 5
= $35
Cost of 17 marbles
= 47 + 35
= $82
(c)
Number of sets of 10 marbles
= 28 ÷ 10
= 2 r 8
Cost of 20 marbles
= 2 x 47
= $94
Cost of 8 marbles
= 8 x 5
= $40
Cost of 28 marbles
= 94 + 40
= $134
Answer(s): (a) $47; (b) $82; (c) $134