Write a common denominator for 1/4 and 5/6

One way to get the common denominator of 1/4 and 5/6 so that it can be added or subtracted, would be to get what is known as the LEAST common denominator. To do this, all you have to do is look for a number that is both a multiple or divisible by both 4 and 6 (the denominators). So we have 12, 24, and 36 as possible candidates. Since we are looking for the least common denominator, then obviously we have to pick the smallest number. So in this case, we will pick 12. 

If you make it a little more clear i can answer it