2 Answers

A fraction from greater to less by 1/6.   So you are subtracting 1/6 from something? That's what this sounds like.  
In order to subtract or add fractions, they need to have the same denominator.  Since I do not know what your other fraction is, I will just make up something so you can get the idea of what to do.

3/4 - 1/6 =    you need to get a common denominator. What is the smallest number that is a multiple of both 4 and 6?   4 x 2 = 8, 4 x 3 = 12 etc.   6 x 2 = 12  AHA!  12 will be the new denominator.  Since you multiple 4 x 3 to get 12, you also multiply the numerator in 3/4 (3) by 3, which keeps the fraction 3/4 intact.   9/12 is still 3/4.  
You multiplied the 6 by 2, so multiply the 1 by 2 also.   2/12 is still 1/6.
Now you have 9/12 - 2/12   The denominator remains /12.  9 - 2 = 7    7/12 is the answer.

1.  Common denominator -  lowest common multiple of both denominators
2.  Subtract only numerator from numerator 
3. Denominator remains
4.  Reduce to lowest fractional form if necessary 

fraction greater to lesser 1/6