To subtract fractions, the denominators need to be the same.

so the original problem is:

1/2z - 1/x

The common denominator for these two fractions is 2xz

So to give the first fraction a denominator of 2xz, you need to multiply the numerator and denominator by x. This will leave us with x/2xz.

To give the second fraction a denominator of 2xz, you need to multiply the numerator and denominator by 2z. This will leave us with 2z/2xz

Now we have:

x/2xz - 2z/2xz

Now because the two fraction have a common denominator, we can combine the numerator. Once you combine the numerator, you are left with:

x-2z/2xz