Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Here's a word problem having to do with percentages, and the answer doesn't make sense. A furniture store is selling a desk for $300. If the store makes a 25% profit on the sale, what is the store's cost for the desk? The answer is $240 but how?


share|cite|improve this question
up vote 1 down vote accepted

Let us say that $x$ is the cost for the store. The store makes a profit of $25$% which means that the selling price is $1.25 x$; so $1.25 x=300$ then $x=300/1.25=240$.

share|cite|improve this answer

Let's say the cost of the desk for the store is 100%. We know 25% more than that is \$300. Hence, 125% of the cost price of the desk is \$300, and the original price is therefore $100\times \frac{\$300}{125}$. Since $\$300/125$ = 1% of cost price, and then we just multiply by 100 to find the original 100%.

share|cite|improve this answer

Use the formula:

$$\frac{\text{percent of change}}{100} = \frac{\text{change in price}}{\text{original price}}$$

Let $x$ = the original price.


$$\frac{1}{4} = \frac{300-x}{x}$$

$x = $ $240.

share|cite|improve this answer
Thanks, skullpatrol. BTW, how do you enter the equations on this site? – Alex Mar 31 '14 at 4:20
This may help :-) – Sᴋᴜʟʟ ᴘᴇᴛʀᴏʟ Mar 31 '14 at 12:28

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.