Please help due tonight

How do you find principle and simple interest

Acarton of juice contains 64 ounces miss wilson bought six cartons of juice how many ounces of juice did she buy

Adolphin is swimming with her friend. the dolphin jumps to a height of 4.54.54, point, 5 meters above the surface of the water as her friend swims 9.89.89, point, 8 meters directly below her. what is the position of the dolphin's friend relative to the surface of the water? meters