Question 865124
width -------xft

length 3x-7 ft

area = L * W

120  =x(3x-7)

120=3x^2-7x

3x^2-7x-120=0

use the formula method

a=	3    	b=	-7    	c=	-120    		
							
b^2-4ac=	49    	-	-1440    				
b^2-4ac=	1489    			{{{sqrt(	1489    	)}}}=	38 3/5
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}							
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}							
x1=(	7    	+	38 3/5	)/	6    		
x1=	7 3/5						
x2=(	7    	-38 3/5	) /	6    			
x2=	-5 1/4						
Ignore negative value			mph				
x	=	7 3/5					

width = 7 3/5

length =3*(38/5) -7
=15 4/5 feet