I found error, when quiz send answer on email

I use rich answers for my question, when quiz send answer on email, i see some error

let you see in picture as below (2 pics).

https://drive.google.com/open?id=1rbmYdNDDuIkOj0jPqgQV24aUYtFUvzjF

https://drive.google.com/open?id=1ZfsCssGf6jhRdBD6d2dU7j9yBoKwUd1c

And let you can test the quiz as: https://quiz.engineer-tutor.com/catc-quiz-math1/