Noise in a quiet room is 500 times as intense as the threshold of sound. What is the decibel measurement for a quiet room

Find the solution of this system of equation -7x+y=-20 9x-3y=36

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

What is the difference between –12 and –5? what is the distance between –12 and –7 on a number line? units