From the set {5, 7, 40}, use substitution to determine which value of x makes the equation true. 7(x + 35) = 280

A. 7
B. none of these
C. 40
D. 5

Please help me

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