I have a question about acids/bases. See below

If 15.0mL of 0.25M HBr is needed to completely neutralize a 75.0mL sample of KOH, what was the initial concentration of the KOH solution?
Please explain.
Thanks so much!

1) Calculate moles of HBr used.

0.015 L x 0.25 mol/L = 0.00375 mol HBr

2) Calculate moles of KOH neutralized.

HBr + KOH -----> KBr + H2O

There is a 1 to 1 mole ratio between HBr and KOH, so moles of KOH
must also be 0.00375 mol

3) Calculate molarity of KOH

0.00375 mol / 0.075 L = 0.050 mol/L or 0.050 M

use MaVa = MbVb

just plug in and solve