1 marble costs $8.
For every 10 marbles bought, a discount of $4 is given.
- How much do 10 marbles cost?
- How much do 12 marbles cost?
- How much do 39 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 8 - 4
= 80 - 4
= $76
(b)
Number of marbles that do not belong to a set
= 12 ÷ 10
= 1 r 2
Cost of the 2 extra marbles
= 2 x 8
= $16
Cost of 12 marbles
= 76 + 16
= $92
(c)
Number of sets of 10 marbles
= 39 ÷ 10
= 3 r 9
Cost of 30 marbles
= 3 x 76
= $228
Cost of 9 marbles
= 9 x 8
= $72
Cost of 39 marbles
= 228 + 72
= $300
Answer(s): (a) $76; (b) $92; (c) $300