Question 894157
A man was 26 years old when his son was born. 
<pre>
Let his son's age now = s.

Then, the man's age now is his son's age now plus 26 years.  So

The man's age now = s+26
</pre>
Now, he is three times as old as his son. 
<pre>
So

His age now = 3 times his son's age now, so

       s+26 = 3s

         26 = 2s
 
         13 = s
</pre>
How old is the son now?
<pre>
He's 13.  [And the man is 3 times as old or 39]

Edwin</pre>