1 marble costs $9.
For every 10 marbles bought, a discount of $7 is given.
- How much do 10 marbles cost?
- How much do 16 marbles cost?
- How much do 26 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 9 - 7
= 90 - 7
= $83
(b)
Number of marbles that do not belong to a set
= 16 ÷ 10
= 1 r 6
Cost of the 6 extra marbles
= 6 x 9
= $54
Cost of 16 marbles
= 83 + 54
= $137
(c)
Number of sets of 10 marbles
= 26 ÷ 10
= 2 r 6
Cost of 20 marbles
= 2 x 83
= $166
Cost of 6 marbles
= 6 x 9
= $54
Cost of 26 marbles
= 166 + 54
= $220
Answer(s): (a) $83; (b) $137; (c) $220