Ответ:

6/x-6/(x+1)=0.2

(6/x-6/(x+1))*x=0.2*x

6/(x+1)=0.2x

6/(x+1)*(x+1)=0.2x*(x+1)

6=0.2x²+0.2x

-0.2x²-0.2x+6=0

D=-0.2²-4*(-0.2)*6=4.84

x1=(√4.84-(-0.2))/(2*(-0.2))=-6

x2=(-√4.84-(-0.2))/(2*(-0.2))=5км/ час