10-2i·i simplifying and rationalizing

If g(x) = x+1/ x-2 and h (x) =4 - x , what is the value of ( g*h) (-3)?

What is the distance between the points (2 -3) and (-6 4) on the coordinate plane

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