Lynn put 3 7/8 gallons of gas in her gas tank. if there are now 18 1/6 gallons in the tank, how many gallons did she start with?? Please I need an answer ASAP worth 25 points

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