Question 706866
Create a table of data information.  Assigning r for speed of the slower, first plane, and then r+50 for the speed of the second, faster plane, we can show this:


Plane____________speed mph________time in hours_________distance miles
First____________r__________________(___)________________500
Second__________r+50________________(___)_______________1000
TOTAL______________________________6.5__________________1500


Some information seems to be missing but we can fill in the missing parts.
speed*time=distance.  This is equivalent to time=(distance)/(speed).


Put in the missing information:

Plane____________speed mph________time in hours_________distance miles
First____________r__________________{{{(500/r)}}}________________500
Second__________r+50________________{{{(1000/(r+50))}}}_________1000
TOTAL______________________________6.5____________________1500


We KNOW how much fly time was used and we can ADD individual time expressions to get the total time, so if we do it:   {{{(500/r)+1000/(r+50)=6.5}}}, we can solve for r, the only variable, the speed of the slow plane, from which we can also find the speed of the faster plane.