Question 483812
x= wind speed
against wind speed = 200-x
with wind speed = 200+x
t=d/r
time return - time forward = 2/3

660/(200-x)-660/(200+x)=2/3

LCD = 3(200-x)(200+x)

Multiply by the LCD

3*660(200+x)-3*660(200-x)=2/3 * (200-x)(200+x)

1980*200+ 1980x-1980*200+1980x=2(200-x)(200+x)

3960x=80000-2x^2

2x^2+3960x-80000=0
/2
x^2+1980x-40000=0

Find the roots of the equation by quadratic formula							
							
a=	1	b=	1980	c=	-40000		
							
b^2-4ac=	3920400	-	160000				
b^2-4ac=	4080400		
{{{sqrt(	4080400	)}}}=	2020
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}							
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}							
x1=(	-1980	+	2020	)/	2		
x1=	20		    				
x2=(	-1980	-2020	) /	2			
x2= 	-2000	    				
Ignore negative value							
x	=	20	mph wind speed
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