Question 468232
speed	x		
speed	x	-	5
			
Distance = same		210	miles
original time – time with increased speed =1			
t=d/t			
210/x-210/(x+5)	=1				
LCD= 	x (x+5)										
multiply by LCD																
210(x+5)-210x=1x(x+5)
210x+1050-210x=1x^2+5x				
1050=1x^2+5x						
x^2+5x-1050=0							
																
a=	1		b=	5		c=		-1050	
x1=(-5+sqrt(25-(	-4200)	)	/	2					
=	4225															
x1=	30															
																
x2=(5-sqrt(25-(-4200))/	2					
																
x2=	-35	
Ignore negative value
speed of car = 30 mph