Question 809412
First Part	x			mph											
Second Part	x		-5	mph											
Total time		5	hours												
First Part	time 	165	/	x											
Second Part	time 	100	/	(	x	-5	)								
															
Time first part + time second part =			5	hours											
															
165	/	x		+	100	/(x	-5	)	=	5					
LCD =	(	x	+	0	)*	(x	-5	)							
multiply the equation by the LCD															
we get															
165	*	(x+	-5								=	5			
165	x+	-825	+	)+	100		x		=	5	X^2			-25	x
290	x+	-825	=	5	X^2		=	0							
5	X^2	-290	x+	825			=	0							
5	X^2+	-290	x+	825	=										
/	5					0									
5	X^2	-290	x+	825	=										
/5
x^2-58x+165=0

factors are -55 & -3

x=55 OR 3

first part 55 mph
second part =50 mph