I know the answer is (1,-1) but how do you get this answer?

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

Find x to the nearest hundredth place

Logan wants to know how many skateboards have defective parts. he inspects 20,000 skateboards and keeps track of the number of defects per board. use his probability distribution table to find the expected value for defects on a skateboard.