In The Commutative & Assertive Law Lesson , I can't insert answer for a certain question

[EskAlam06]

I can't insert answer for a certain question as every time I click on the answer bar , it just takes me to the top of the page which makes it unable to actually insert any answer and proceed to next steps.

Steps-

1. Open The Commutative & Assertive Law Lesson
2. Proceed to the certain where it asks to enter expression
3. Try entering expression

Expected Behavior- You should be able enter the expression

Actual Behavior- It's not enabling to enter the expression

Screenshot-