Question 894484
RT=D rate time distance, uniform rates relationship.


Your two planes are flying in opposite directions, departing the same location at the same time.  Look at this table using implied variable assignments:


____________________rate______time______distance
To EAST______________r_________3________r*3
To WEST_____________2r_________3________2r*3
Total___________________________________2700, their distance appart, the sum of their distances traveled.


Obvious enough?
{{{r*3+2r*3=2700}}}
{{{3r+6r=2700}}}
{{{9r=2700}}}
{{{highlight(r=300)}}}-----the slow plane going east.
{{{2*300=highlight(600)}}}------the faster plane going west.


When you can understand this form of problem clearly enough, you could learn to take the shorcut:
that because going in opposite directions, at r and 2r, the rate of separation happening is {{{r+2r=3r}}}.  If then t and d are known, you simply form {{{3r*t=d}}} and solve for r.
NOTE:  Do not try to take the shortcut until you really understand it.  Use your ability to analyze the problem using pictures expressions equations and tables of data.