A husband wrote the following letter for his wife and left it on the dining room table:

"To My Dear Wife,

You will surely understand that I have certain needs that you, being 54 years old, can no longer satisfy. I am very happy with you and I value you as a good wife. Therefore after reading this letter I hope 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 upset ~ I shall be back home before midnight."

When the man came home late that night he found the following letter on the dining room table:

I received your letter and thank you for your honesty about my being 54 years old.

I would like to take this opportunity to remind you that you are also 54 years old. As you know I am a math teacher at our local college.  I would like to inform you that while you're at the Comfort Inn, I will be at the Hotel Fiesta with Michael, one of my students, who is also the assistant tennis coach. He is young, virile, and like your secretary, is 18 years old.  

As a successful businessman with an excellent knowledge of math you will understand that we are in the same situation, although with one small difference; 18 goes into 54 a lot more times than 54 goes into 18.  Therefore I will not be home until sometime tomorrow."