Kyla was asked to solve the system of equation below. she made the graph shown and stated that the solution of the system is (-4,-1). is kyla correct? justify your response and identify kyla's errors, if they exist.

x+y=3
x-3y=-1

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