A10.0 milliliter sample of naoh (aq) is neutralized by 40.0 milliliters of 0.50 m hcl. what is the molarity of the naoh (aq)?

the answer is 2.0m but i am unsure how to do the math. someone

moles of HCl =  (molarity) * (volume)
                     = 
                     = 0.02 mol 
                   
     mole ratio of NaOH : HCl according to the equation is  1 : 1
     ∴ mol of NaOH = mol of HCl
                              =  0.02mol

Since volume of NaOH is 0.010 

then molarity of NaOH = 
                                     = 
                                     = 

Note:  
1)  is the same as M
2) I converted the ml to l then to