molar mass HCl = 36.5 g/mol and NaOH = 40.0 g/mol
molarity of NaOH = 1.0 M
Volume of NaOH = 20.00 mL in liters : 20.00 / 1000 = 0.02 L
Number of moles NaOH :
n = M * V
n = 1.0 * 0.02
n = 0.02 moles Of NaOH
Finally Molarity of the acid solution
Volume HCl : 15.0 mL in liters : 15.0 / 1000 = 0.015 L
1 HCl + 1 NaOH = 1 H₂O + 1 NaCl
1 mole HCl --------- 1 mole NaOH
? mole HCl --------- 0.02 moles NaOH
moles HCl = 0.02 * 1 / 1
= 0.02 moles of HCl
M ( HCl) = n / V
= 0.02 / 0.015
= 1.333 M of HCl
hope this helps!