1 marble costs $7.
For every 10 marbles bought, a discount of $6 is given.
- How much do 10 marbles cost?
- How much do 19 marbles cost?
- How much do 22 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 7 - 6
= 70 - 6
= $64
(b)
Number of marbles that do not belong to a set
= 19 ÷ 10
= 1 r 9
Cost of the 9 extra marbles
= 9 x 7
= $63
Cost of 19 marbles
= 64 + 63
= $127
(c)
Number of sets of 10 marbles
= 22 ÷ 10
= 2 r 2
Cost of 20 marbles
= 2 x 64
= $128
Cost of 2 marbles
= 2 x 7
= $14
Cost of 22 marbles
= 128 + 14
= $142
Answer(s): (a) $64; (b) $127; (c) $142