Calculate how many mg of potassium hydroxy are needed to neutralize 75mg of mefenamic acid .

Snow, Taylor, et al. You really need to learn to express your question in terms that others can understand, especially if you want help. I assume you mean potassium hydroxide. I will call fenenamic acid HA since it has only 1 H to be neutralized.

KOH + HA ==> H2O + HA
mols HA = grams HA/molar mass HA
mols KOH required = mols HA to start.
Then grams KOH required = mols KOH x molar mass KOH, then convert to mg.