Question

A pen costs twice as much as a pencil. 7 pens and 12 pencils cost a total of $6.50. What is the price of one pencil?

- Please show your work, I know the answer, but I just don’t know HOW to get the answer.

Answer 1

$ 2.167

Explanation:

Let the cost of a pencil be x and that of a pen be y.

A pen costs twice as much as a pencil.

==> cost of a pen = 2 × cost of a pencil

==> y = 2x

Their total cost is $6.50

==> x + y = $6.50

since y = 2x, substituting y for 2x

==> x + 2x = 6.50

==> 3x = 6.50

dividing both sides by 3

==> x = 2.16

As per our assumption, x is the cost of one pencil.

Therefore, the cost of a pencil is $2.167