Puzzle ZWPF 

Workings

Hint
The answer is a whole number less than 10.

Answer
3.

Reasoning
We can multiply throughout by 12,
    X     X     X     X
    -  -  -  +  -  =  -
    X     2     4     12

to give:

   12 − 6X + 3X = X

        12 − 3X = X

             12 = 4X

              3 = X

As required.

Double-Checking
    3     3     3     3
    -  -  -  +  -  =  -
    3     2     4     12

    1 − 1.5 + 0.75 = 0.25

              0.25 = 0.25, which confirms that 3 is correct.