1 marble costs $9.
For every 10 marbles bought, a discount of $5 is given.
- How much do 10 marbles cost?
- How much do 19 marbles cost?
- How much do 26 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 9 - 5
= 90 - 5
= $85
(b)
Number of marbles that do not belong to a set
= 19 ÷ 10
= 1 r 9
Cost of the 9 extra marbles
= 9 x 9
= $81
Cost of 19 marbles
= 85 + 81
= $166
(c)
Number of sets of 10 marbles
= 26 ÷ 10
= 2 r 6
Cost of 20 marbles
= 2 x 85
= $170
Cost of 6 marbles
= 6 x 9
= $54
Cost of 26 marbles
= 170 + 54
= $224
Answer(s): (a) $85; (b) $166; (c) $224