A father said to his son, "I was as old as you are at the present at the time of your birth". If the father's age is 48 years now, what was the son's age nine years back?
There is something I don't understand about algebra: It has been around for thousands of years, yet no one has ever found out what the value of "x" or "y" really is.
Richard van der Merwe
Life is good for only two things, discovering mathematics and teaching mathematics.