A businessman sends a fax to his wife:

To My Dear Wife,
You will surely understand that I have certain needs that you with your 54 years can no longer supply. I am very happy with you and value you as a good wife.

Therefore after reading this fax, I hope that you will not
wrongly interpret the fact that I will be spending the evening with my 18 year old secretary at the Comfort Inn Hotel. Please don't be perturbed I shall be back home before midnight.

When the man came home, he found the following letter on the dining room table.

My Dear Husband,
I received your fax and thank you for your honesty. I would like to take this opportunity to remind you that you are also 54 years old. At the same time I would like to inform you that while you read this, I will be at the Hotel Fiesta with Michael my tennis coach, who like your secretary is also 18 years old.

As a successful businessman and with your excellent knowledge of Math, you will understand that we are in the same situation, although with one small difference. 18 goes into 54 more often than 54 goes into 18. Therefore I will not be back before lunch time tomorrow.