Let the aeroplane covers xkm at a speed of 440km∕h and (x−770)km at a speed of 660km∕h. Hence, it covers a total distance of (2x−770)km at a speed of 500km∕h.
Average speed =
Totaldistance
Totaltime
⇒ 500=
2x−770
x
440
+
x−770
660
or
2x−770
500
=
x
440
+
x−770
660
orx=1760 Therefore, the total distance covered =2x−770 =2×1760−770=2750km