Question 985093
<pre> 
           speed     time     distance
Kali         r        t+1       d
Ndiba       r+15       t        d

 </pre>

After two hours, Ndiba caught-up.

 
<pre>

            speed     time       distance
Kali         r        2+1=3       d
Ndiba       r+15       2          d

</pre>


Uniform Rates Rule for Travel, RT=D.
{{{system(r*3=d,(r+15)*2=d)}}}