Question

If it takes 20.0 mL of 1.200 M KOH to neutralize 60.0 mL of a given H3PO4 solution, what is the molarity of this phosphoric acid solution?

I've figured out that the neutralization of phosphoric acid by the addition of potassium hydroxide in aqueous solution: H3PO4 + 3 KOH -> K3PO4 +3 H2O

Answer 1

You've done step 1.
Step 2.
mols KOH = M x L KOH = ?

Step 3.
Using the coefficients in the balanced equation, convert mols KOH to mols H3PO4. You can see that mols H3PO4 = 1/3 mols KOH

Step 4.
Then M H3PO4 = mols H3PO4/L H3PO4 = ?