Oh, this is easy.
All you have to do is turn the 5% into a number. This is done by moving the decimal place two places to the left (the decimal place, in THIS case, is the percent sign). You get .05
Now, simply divide. Yes, this is a tricky part. When dealing with whole numbers and decimals, multiplecation is quite useless for cases like this, it simply makes the number SMALLER. If you want to find out what the ORIGINAL number was, you DIVIDE.
So, 550/.05
You get 11,000
This is your original number. That means 550 is 5% of 11,000
To check this, NOW use the inverse, multiplication. 11,000*.05=550
Your answer is 11,000