If you subtract two values that have uncertainty do you add the uncertainty? Do you use absolute uncertainty and then turn it into relative uncertainty somehow or can you use the relative uncertainty?
I am doing an assignment on isotonic points for vegetables. I have found percentage change for mass and have uncertainty for initial and final mass and I need to be able to say something like for the found isotonic point relative uncertainty for initial is -+20% and for final it is -+24% therefore the uncertainty for the isotonic point is ____.
Not sure if that makes sense but I tried.