If 30 pens cost $22, how many pens can I buy for $8?

Answer 1

Hi Douglas!

You can think about this in multiple ways.

You can figure out the unit cost per pen by dividing $22 by 30 pens.

22 / 30 = $0.733 per pen.

Then you can divide $8 (the amount you have to spend) by $0.733 (the cost per pen).

$8 / 0.733 = 10.91 pens.

We can also think about it by setting up an equation and cross multiplying, where "z" is the number of pens you can buy for $8.

30 pens / $22 = z pens / $8

cross multiply:

30*8 = 22*z

240 = 22*z

240 / 22 = z

z = 10.91 pens

You can only buy whole numbers of pens, so the answer is you can get 10 pens for $8.