To find the difference of 7 - 3 5/12, how do you rename the 7?

I assume you want a common denominator.

So you see that the 5/12 has a denominator of 12, so you need to rename the 7 so it also has a denominator of 12.

7 is the same as 7/1. So multiply the numerator and denominator by 12 to get 84/12.