1 marble costs $7.
For every 10 marbles bought, a discount of $7 is given.
- How much do 10 marbles cost?
- How much do 17 marbles cost?
- How much do 35 marbles cost?
(a)
Cost of every 10 marbles
= 10 x 7 - 7
= 70 - 7
= $63
(b)
Number of marbles that do not belong to a set
= 17 ÷ 10
= 1 r 7
Cost of the 7 extra marbles
= 7 x 7
= $49
Cost of 17 marbles
= 63 + 49
= $112
(c)
Number of sets of 10 marbles
= 35 ÷ 10
= 3 r 5
Cost of 30 marbles
= 3 x 63
= $189
Cost of 5 marbles
= 5 x 7
= $35
Cost of 35 marbles
= 189 + 35
= $224
Answer(s): (a) $63; (b) $112; (c) $224