Please help I have a timed test will give brainiest ;-;
Which equation, when solved, results in a different value of x than the other three?
-7/8 7 x-3/4=20
3/4+7/8x-20
-7(1/8)x-3/4=20
-7/8(-8/7)x-3/4=20(-8/7)

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