1500/(300+1.5x)=1500/x-4 =(1500-4x)/x
1500x=(300+1.5x)*(1500-4x)=450000-1200x+2250x-6x^2
6x^2+450x-450000=0
x^2+75x-75000=0
x1=-37.5+((37.5)^2+75000)^0.5=238.9168
x1=-37.5-((37.5)^2+75000)^0.5=-313.9168
1500/(300+1.5x)=1500/x-4 =(1500-4x)/x
1500x=(300+1.5x)*(1500-4x)=450000-1200x+2250x-6x^2
6x^2+450x-450000=0
x^2+75x-75000=0
x1=-37.5+((37.5)^2+75000)^0.5=238.9168
x1=-37.5-((37.5)^2+75000)^0.5=-313.9168