First, let's make all the fractions equivalent to make the problem easier to solve.
5/12 can stay as 5/12
5/4 = 15/12
2/3 = 8/12
Now the problem is 5/12 - ___ + 15/12 = 8/12
Let's add 5/12 and 15/12, which = 20/12.
Now the problem is 20/12 - ___ = 8/12, which is simple.
20 - 12 = 8, so 20/12 - 12/12, or 1, = 8/12.
So 5/12 - 1 + 5/4 = 2/3.
The answer is 1.
Hope this helps!