Hi please help with algebra 1(best if you could explain how you got the answer)

Adriveway is 40 yards long about how many meters long is it

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters