From the equation given in the question we can see that one mole of hydrochloric acid (HCl) reacts with one mole of sodium hydroxide (NaOH).
The first thing to do is to work out the number of moles of sodium hydroxide that reacted by using the equation n = cv (number of moles = concentration x volume).
To do this we need to convert the volume 28.60 cm3 into dm3 (which is the same as litres). There are 1000 cm3 in a dm3 so
28.60 cm3 = 28.60 / 1000 dm3 = 0.0286 dm3
Now we can use n = cv = 0.200 moles per dm3 x 0.0286 dm3 = 0.00572 moles of sodium hydroxide
Since one mole of hydrochloric acid reacts with one mole of sodium hydroxide, 0.00572 moles of hydrochloric acid reacted.
We can now use the equation n=cv and rearrange it to c = n/v to find the concentration of hydrochloric acid.
The volume of hydrochloric acid again needs converting to dm3:
25.00 cm3 = 25.00/1000 dm3 = 0.025 dm3
c = n/v = 0.00572 moles / 0.025 dm3 = 0.23 moles per dm3