Question 1103571
<pre>
              SPEED        TIME       DISTANCE
A             r             t          6300
B             r+50         t-3         4500
</pre>



--------------------------------
,... three hours less time.
--------------------------------


<pre>
              SPEED        TIME           DISTANCE
A             r             6300/r          6300
B             r+50         4500/(r+50)      4500
Difference                  3
</pre>

Now only one variable is needed, that of either plane, here choosing r for plane A.
{{{6300/r-4500/(r+50)=3}}}
Solve for r.