I am 42 years old and my son 4.
In what year will my age be 20 times that of my son?
If we express the statement in the form of mathematical equation where X It is the number of years left to be 20 times the age of my son, we have to:
42 + X = 20 × (4 + X)
Clearing we get X = -2
Which means that two years ago My son's age was 20 times mine, I was 40 and 2.