Hey can someone help me with these math problems

The equation y=mx+b is the slope-intercept form of the equation of a line. what is the equation solved for b? y-m=b y-mx=b y/mx=b y/m-x=b

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

Sawsan recorded the favorite sport of students at her school. she surveyed 200 students. how many students chose tennis?