Question 571015
Corporate jet	B	x	mph					
Commercial jet	A	120	faster					
								
Corporate jet		1260	miles					
Commercial jet		1620	miles					
Corporate jet	time	=	Commercial jet		time			
								
1260	/	x	=	1620	/(	x	+	120
cross multiply								
1260	(	x	+	120	)	=	1620	x
1260	x	+	151200	=	1620	x		
1620	x	-	1260	x	=	151200		
360	x	=	151200					
/	360							
x	=	420      	mph					
420    	mph	Corporate jet						
540	mph	Commercial jet