1 marble costs $4.
For every 10 marbles bought, a discount of $6 is given.
- How much do 10 marbles cost?
- How much do 12 marbles cost?
- How much do 28 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 4 - 6
= 40 - 6
= $34
(b)
Number of marbles that do not belong to a set
= 12 ÷ 10
= 1 r 2
Cost of the 2 extra marbles
= 2 x 4
= $8
Cost of 12 marbles
= 34 + 8
= $42
(c)
Number of sets of 10 marbles
= 28 ÷ 10
= 2 r 8
Cost of 20 marbles
= 2 x 34
= $68
Cost of 8 marbles
= 8 x 4
= $32
Cost of 28 marbles
= 68 + 32
= $100
Answer(s): (a) $34; (b) $42; (c) $100