Mistake in exercise

Hi,

I don't understand the following exercise at Formal Letter Writing.

"Question #: 7: Dear Mr John Smith, This is a correct on an envelope.
User's answer: False
Correct answer: True
Additional Notes: You can you both names on the envelope."

I cut and pasted the exercise. It looks like both the question and the Additional Notes are grammatically incorrect.
Would you please look into it and let me know the correct sentences?

Thanks,

Julika

[Casiopea]

Well, you're right. There are a few errors. It should read:

#7 Mr John Smith
Question: Is this correct on an envelope?
Answer: Yes. It's correct.
Additional Notes: You can use both names on the envelope.

By the way, "dear" is never used on an envelope.