need help quick

Do you address the outside envolpe with guest or only the inside?

For example
Mr. Bart Simspon and Guest

or
Mr. Bart Simspon

Inside Bart & Guest.. My spreadsheet is due by tonight thanks.
Danielle

My instructions said
If the couple is unmarried and living togtger, both their names are on the address on the outside i.e.
Mr. John Smith
Ms. Mary Jones
Address

Use '& guest' only on the inside envelope if you are using one. Include name of guest though if know.

Yes, you would write 'and Guest' on the inner envelope but it would be better if you could find out the guest's name. If you just don't know, 'and Guest' is suitable.

On the outside envelope, Mr. Bart Jones is acceptable if you don't know the guest's name. Don't put 'and Guest' on the outer envelope.