What rate describes a unit price

Which equation represents a direct linear variationa. y=x2b. y=2/5xc. y=1/xd. y=x+3

If np3 /nc2 = 6, find the value of n

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