Solve these questions. Pls show your work.

Samantha swam upstream for some distance in one hour. she then swam downstream the same river for the same distance in only 12 minutes. if the river flows at 4 mph, how fast can samantha swim in still water?

The perimeter of a movie screen is 54 meters. the screen is 18 meters wide. how tall is it?

Peter measures the angles in a triangle. he finds that the angles are 95, 10 and 75. is he correct? explain your answer