Wrong answer

[nefton]

http://dragon-book.jcf94.com/book/ch02/2.2/2.2.html
question 2.2.4 unit 4 and 5
"Arithmetic expressions of integers and identifiers with the four binary operators +, -, *, /."
there are no " ( ) " in the answer.
so "factor -> id | num | (expr)" should be "factor -> id | num"