Help me pls I don't understand

The probability that a college student belongs to a health club is 0.3. the probability that a college student lives off-campus is 0.4. the probability that a college student belongs to a health club and lives off-campus is 0.12. find the probability that a college student belongs to a health club or lives off-campus. tip: p(a or b) = p(a) + p(b) - p(a and b) 0.54 0.58 0.70 0.82

In the triangles, tr = ge and sr = fe. if = 3.2 ft, which is a possible measure of ? 1.6 ft 3.0 ft 3.2 ft 4.0 ft

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