1 marble costs $9.
For every 10 marbles bought, a discount of $3 is given.
- How much do 10 marbles cost?
- How much do 12 marbles cost?
- How much do 26 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 9 - 3
= 90 - 3
= $87
(b)
Number of marbles that do not belong to a set
= 12 ÷ 10
= 1 r 2
Cost of the 2 extra marbles
= 2 x 9
= $18
Cost of 12 marbles
= 87 + 18
= $105
(c)
Number of sets of 10 marbles
= 26 ÷ 10
= 2 r 6
Cost of 20 marbles
= 2 x 87
= $174
Cost of 6 marbles
= 6 x 9
= $54
Cost of 26 marbles
= 174 + 54
= $228
Answer(s): (a) $87; (b) $105; (c) $228