Fix bug with First Set Tutorial question
Fix bug with First Set Tutorial question

To get this bug, first answer the ninth First Set question incorrectly,
   and then change it to the correct answer (which is "x, y, z"). It
   will still say that it is the incorrect answer. Most likely a problem
   with the parser.

H-Huang/LL1-Academy,H-Huang/LL1-Academy,H-Huang/LL1-Academy,H-Huang/LL1-Academy