We know $65 were spent on his ticket and some shirts.Which he used 32.25 which leaves us  with 27.75 and a shirt cost 14 and 50 cent .
SO you need to divide 27.75 in 14 and 50 cents which is equal to
   
             14 plus 14 equals 28
              75 plus 50 equals 1 and 25 cents
David can buy two shirts 
Hope this helped