Just plug and chug. Since the question asks for percents, pick 100. (but any number will do.)

100/50 + 100/25= 2+4 =6

6 is 6% of 100.

a direct approach is also not bad

(3X/50)(100/X)=6

A lot of people jump to a smart number of 100. The confusing part can come when you are asking "what percent of x" (i.e "what percent of 100"). Therefore, you can avoid this by choosing a different smart number which is a multiple of 50 and 25 --> 50.


Therefore:
if X=50
\(\frac{50}{50}\) + \(\frac{50}{25}\) = 1 + 2 = 3

Because we need to figure out the percent of X, we must then take our new fraction \(\frac{3}{50}\) and multiply by 100 to form a percent. Cross multiplication will work fine. \(\frac{3}{50}\) = \(\frac{x}{100}\)

Notice that you can just multiple \(\frac{3}{50}\) * \(\frac{2}{2}\) because this is essentially multiplying by 1 and that will change the denominator to 100 leaving you with \(\frac{6}{100}\) or 6%

Written differently: notice that the denominator in \(\frac{3}{50}\) is 50. Thus, you can make the denominator 100 in order to get a percentage. To do so, you must multiply 50 * 2. Do not forget that if you multiply the denominator by 2, you must also multiply the numerator by 2.

Answer = A

Take x as 100.

x/50 + x/25 = 100/50 + 100/25 = 2 + 4 = 6

So 6%. Option A

Posted from my mobile device

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________