Question 664870
Plane I		x	mph						
Plane II		50	faster	x	+	50	mph		
									
Plane I		165	miles						
Plane II		240	miles						
Plane I	time	=	Plane II		time				
t=d/r									
165	/	x	=	240	/(	x	+	50	)
cross multiply									
165	(	x	+	50	)	=	240	x	
165	x	+	8250	=	240	x			
165	x	-	240	x	=	-8250			
-75	x	=	-8250						
/	-75								
x	=	110      	mph	

Plane I		110	mph						
Plane II		50	faster	110	+	50	=160 mph