1 marble costs $3.
For every 10 marbles bought, a discount of $5 is given.
- How much do 10 marbles cost?
- How much do 14 marbles cost?
- How much do 28 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 3 - 5
= 30 - 5
= $25
(b)
Number of marbles that do not belong to a set
= 14 ÷ 10
= 1 r 4
Cost of the 4 extra marbles
= 4 x 3
= $12
Cost of 14 marbles
= 25 + 12
= $37
(c)
Number of sets of 10 marbles
= 28 ÷ 10
= 2 r 8
Cost of 20 marbles
= 2 x 25
= $50
Cost of 8 marbles
= 8 x 3
= $24
Cost of 28 marbles
= 50 + 24
= $74
Answer(s): (a) $25; (b) $37; (c) $74