1 marble costs $5.
For every 10 marbles bought, a discount of $3 is given.
- How much do 10 marbles cost?
- How much do 18 marbles cost?
- How much do 34 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 5 - 3
= 50 - 3
= $47
(b)
Number of marbles that do not belong to a set
= 18 ÷ 10
= 1 r 8
Cost of the 8 extra marbles
= 8 x 5
= $40
Cost of 18 marbles
= 47 + 40
= $87
(c)
Number of sets of 10 marbles
= 34 ÷ 10
= 3 r 4
Cost of 30 marbles
= 3 x 47
= $141
Cost of 4 marbles
= 4 x 5
= $20
Cost of 34 marbles
= 141 + 20
= $161
Answer(s): (a) $47; (b) $87; (c) $161