Question 787013
I am driving at x mph
friend is driving at (x+6) mph

After 2 hours

you have driven 2x miles
your friend 2(x+6) miles

I , my friend and the starting point form a right triangle 

Apply Pythagoras theorem

(2x)^2+(2(x+6))^2=161.44^2

4x^2+4(x^2+12x+36)=161.44^2

4x^2+4x^2+48x+144=26062.87

8x^2+48x=26,062.87-144

8x^2+48x-25918.87=0

a=	8	,	b=	48	,	c=	-25918.87
							
b^2-4ac=	2304	+	829403.84				
b^2-4ac=	831707.84						
{{{	sqrt(	831707.84	)=	911.98	}}}		
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}							
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}							
x1=(	-48	+	911.98	)/	16		
x1=	54.00						
{{{x2=(-b-sqrt(b^2-4ac))/(2a)}}}							
x2=(	-48	-911.98	) /	16			
x2=	-60.00						
Ignore negative value							
	speed	54	mph				
							
m.ananth@hotmail.ca