The expenses of a tea party are partly constant and partly vary directly with the number of guest. when there are 60 guest, the expenses are $2100.when there are 150 guest , the expenses are $4800.find the expenses when there are 200 guest

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