Is a simple random sample is valid true or never true or always or sometimes

Empty box + box + empty box fill in the box is equal to 30 how

Abird on top of a 200 ft bridge tower sees a man standing on the lower part of the bridge (which is 50 ft above the ground). the angle of depression from the bird is 26 ̊. how far is the man from the base of the bridge tower? with explanation and pictures .

3x + 4y = 5 x- 3y = -7 solve by substitution