Question 1027769
Mr. John traveled to a city 120 miles from his home to attend a meeting. 
speed be x mph

 Due to car trouble, his average speed returning was 12 mph less than his speed going. 
x-12 mph

 If the total time for the round trip was 4 hours,

time going + time returning = 4

t=d/r

{{{120/x+120/(x-12)=4}}}


120(x-12) + 120x = 4x(x-12)


120x-1440+120x=4x^2-48x


4x^2-288x+1440=0

/4

x^2-72x+360=0

Find roots of the quadratic equation											
a=	1		b=	-72		c=	360				
											
x1=	(	72	+	sqrt(		5184	-	-1440	))	/	2
x1=(	72	+	61.19	)/	2						
x1=	66.59										
											
x2=	(	-7	-	sqrt(		49	-	20	)	/	2
x2=(	72	-	61.19	)/	2						
x2=	5.41										
Going speed was 66.6 mph