Question 1044407
<pre>
                  SPEED        TIME        DISTANCE

Going there         r           t+1          d

Coming back         75           t           d

Total                         (t+1)+t        2d

AVERAGE            50
</pre>

Three unknown variables.  Basic rule RT=D for travel rates.


{{{system(r(t+1)=d,75t=d,2d/(t+(t+1))=50)}}}


You can solve for all three variables, but the question asks for solution and value of {{{(t+1)+t}}}, the time for the whole trip , as round-trip.