1 marble costs $3.
For every 10 marbles bought, a discount of $3 is given.
- How much do 10 marbles cost?
- How much do 16 marbles cost?
- How much do 24 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 3 - 3
= 30 - 3
= $27
(b)
Number of marbles that do not belong to a set
= 16 ÷ 10
= 1 r 6
Cost of the 6 extra marbles
= 6 x 3
= $18
Cost of 16 marbles
= 27 + 18
= $45
(c)
Number of sets of 10 marbles
= 24 ÷ 10
= 2 r 4
Cost of 20 marbles
= 2 x 27
= $54
Cost of 4 marbles
= 4 x 3
= $12
Cost of 24 marbles
= 54 + 12
= $66
Answer(s): (a) $27; (b) $45; (c) $66