<PRE><B>Question 85433</B>
Let time taken for second part be = x hours
Then time taken for First part =x+1 hours

Now From given data  560 miles in x+1 hours...Eqn 1
Now From given data  480 miles in x   hours...Eqn 2
Subtracting          080 miles  in (x+1)-x=1 hour
The  speed of plane is 80 miles per hour

Time for second portion = 480/80 = 6 hours
OK
</PRE>