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 35 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
= 35 ÷ 10
= 3 r 5
Cost of 30 marbles
= 3 x 83
= $249
Cost of 5 marbles
= 5 x 9
= $45
Cost of 35 marbles
= 249 + 45
= $294
Answer(s): (a) $83; (b) $137; (c) $294