[calaren]

Ok, here it is:

The figure below is a titration cure for a weak monoprotic acid that is titrated with a strong base (NaOH).

[Insert figure here]

From the figure, I got that the volume at the equivalence point is 12.5mL, the pK_a is 8.5, and the K_a is 0.929.

The next part of the question is:

What is the molar concentration of the acid if a 25.00mL was used in the trial?

No starting molar concentration was given, and I don't know how to get the molar concentration from the pK_a, K_a, and all that. I've looked all over the web, and I'm having trouble finding anything that would explain it. 

[AWK]

the pKa is 8.5, and the Ka is 0.929

[Borek]

What is the molar concentration of the acid if a 25.00mL was used in the trial?

Usually we calculate such things knowing concentration of the titrant. To some extent it is possible to evaluate concentration of acid knowing pH at equivalence point (pH is a function of concentration and concentration is a function of pH), but accuracy is low.