Answer :

7 1/12  -  2 3/4

First we have to change mixed numbers to improper fractions

7 1/12  =  7 x 12 + 1 = 85   85/12

2 3/4  =  2 x 4 + 3 =  11     11/4

 85/12 - 11/4

Now we need to find the LCD (least common denominator) for 4 and 12

4, 8, 12

12

12 is our LCD, so it becomes our new denominator

85/12 would stay the same because the denominator wasn't changed but for 11/4 our new denominator is 12, so our fraction will change.

11/4  =  33/12 

4 goes into 12, 3 times. What you do to the bottom, you do to the top.

3 x 11 = 33

3 x 4 = 12

So, our new fraction is 33/12.  Now we subtract

85/12  -  33/12  =  52/12

Now we convert back to a mixed number

52 ÷ 12 = 4 4/12 reduce

4 1/3

Hope this helps.