1/2 divided by 1/4 using simplest form showing work

Question and answers are in the attached picture. you so much in advance.

Explain how you can use the associative property to evaluate (7x50)x4.

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