Medium
A father tells his son, 'When you were born, I was as old as you are now.' If the father's present age is 36 years, what was the son's age 5 years ago?
Explanation
Explanation
Let the son's present age be S. At the son's birth, the father's age was 36−S, and this equals S. Thus 36−S=S, so S=18. Therefore, the son's age 5 years ago was 18−5=13 years.
PRO TIP
Re-check your working by substituting the answer back into the original question.