Can you please explain how i can work through these problems?

Suppose that 3% of all athletes are using the endurance-enhancing hormone epo (you should be able to simply compute the percentage of all athletes that are not using epo). for our purposes, a “positive” test result is one that indicates presence of epo in an athlete’s bloodstream. the probability of a positive result, given the presence of epo is .99. the probability of a negative result, when epo is not present, is .90. what is the probability that a randomly selected athlete tests positive for epo? 0.0297

Choose the equation below that represents the line that passes through the point (2, 4) and has a slope of 3. a) y − 4 = 3(x − 2) b) y − 2 = 3(x − 4) c) y + 4 = 3(x + 2) d) y + 2 = 3(x + 4)

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.