the overall cost is $50.33. you now subtract out the prices you know. The easiest way to do that is to add them up; 17.97+25.49. That is 43.46.
The next step is to subtract 43.46 from 50.33. 50.33-43.46=6.87. That is the price of all the pairs of socks put together.
to find out how much one pair is, you then divide 6.87 by 3. That is 2.29.
The answer is $2.29
I hope this helps!