NaOH: n=vm

n= 25.00 cm3 x 1.0 mol

n= 25.00 moldm3/1000

n= 0.025 moldm3

Your units are all over the place

n = 25 cm

^{3} x 1.0 mol/dm

^{3} (I presume)

n = 0.025 dm

^{3} x 1.0 mol/dm

^{3}n = 0.025 mol

NaOH reacts with AcOH in a 1:1 molar ratio, so at the end point you have 0.025 mol AcOH. I presume 24.10 cm

^{3} is the volume of AcOH solution at the end point.

c=m/v

You have already used m for molar concentration, and n for moles. Be consistent. c = m = n/v

c= 24.10 cm3/0.025mol

Why are you dividing volume by moles? c = n/v = 0.025 mol/24.10 cm

^{3}Proceed from here, and get the units right.