Question 1200145
<pre>
Teacher              T
the son              T-24
the grandson         T-49       ----He, in turn is 25 years older than my grandson. 
Teacher+Grandson     73
</pre>

{{{T+(T-49)=73}}}

-

{{{2T=73+49}}}

{{{2T=122}}}

{{{T=61}}}-------------Age of teacher