Question 431703
Plane A x				800	miles			
Plane B	x+15			1000	miles			
										
t=d/r	Time  Plane A		=	Time	Plane B					
800/x=1000/(x+15)
Cross multiply						
800(x+15)=1000*	x	
800x+12000=1000	x				
1000x-800x=12000				
200x=12000							
/200									
x=60	Plane A 	mph						
75	Plane B 	mph