Me. struggling with the actual question

Which expression is equivalent to? assume x > 0 and y > 0.

The depth of a lake at a certain point, wich is a function of the distance of that point from shore, is 30 feet.

Ablock of wood is a cube whose side is x in. long. you cut off a 1-inch thick piece from the entire right side. then you cut off a 3-inch thick piece from the entire top of the remaining shape. the volume of the remaining block is 2,002 in3. what are the dimensions of the original block of wood?