You have 2 movable weighing scales.
Their least count is 1 gram.
You have tried both to find out your weight, but they give you different answers.
You do not know whether both of them are broken, or only one of them is broken.
You know the problem of a weighing scale is:
If your actual weight is $A$, then it will show $A+C$. ($C$ is a constant for that scale, which can be negative.)
Without fixing your scales, how do you determine your weight correctly?
- If there is nothing on a scale, it shows no reading (so you cannot determine $C$ by "weighing nothing")
- You do not know the constant errors ($C$) of your scales
- You do not have any other things to check your weight