The formula for the reaction is
"HCl" + "KOH" -> "KCl" + "H"_2"O"HCl+KOH→KCl+H2O
and its already balanced (yea!).
When the mL and M of something ("KOH")(KOH) is givenm use cross multiplication to find how many mols (remember "M"M is "mol/liter"mol/liter, or "mol/1000 mL"mol/1000 mL):
"0.1250 mol"/"1000 mL" = "x mol"/ "25.81 mL"0.1250 mol1000 mL=x mol25.81 mL
to get 3.23xx10^-33.23×10−3 "moles KOH"moles KOH, and since in the reaction equation all coefficients are 1, that means there were 3.23xx10^-33.23×10−3 "moles"moles of "HCl"HCl in the "50 mL"50 mL sample.
Then, you use cross multiplication again to find how many moles would be in "1000 mL"1000 mL of that sample:
"x mol"/"1000 mL" = (3.23xx10^-3 "mol")/ "50 mL"x mol1000 mL=3.23×10−3mol50 mL
which will give you "0.065 mol/1000 mL"0.065 mol/1000 mL, which is "0.065 M"0.065 M.