Aconsists all elements of b if and only if a union b is equal to b

Josephine has a great garden with and area of 2x2 + x - 6 square feet

One positive number is 9 more than twice another. if their product is 95, find the numbers

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