Sarah eats 18 chicken wings, her friends takes 40 out of the bucket how many will she have left ( she has 60 wings total ).

Really need on these. i have no idea what to do

Simplify the expression. -2/5(10+15m-20n)

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