How to Calculate Absolute Error in Moles for an Acid-Base Titration Experiment?

[thinktank75]

How do you calculate the absolute error of an experiment (in moles of acides) when you are given:

18.59 +/-0.02mL of a 12.85 +/ 0.03M NaOh solution that is going to be neutralized with an unknown acid?

I'm not sure how to plug it into the equation, or I may be using the wrong equation.
Thanks

 

[thinktank75]

I took the greatest possible error (18.59 + 12.85) then subtracted it by the maximum error (18.59 + 0.02) + (12.85 + 0.03) but i keep getting the wrong answer, am I suppose to convert the mL to M? (they're both different, but I can't find the mL for NaOh since I don't have the moles) ...