On a loan of $1200 at 15% annual interest, shirley had to pay $135 interest. for how many months did she have the loan?

Iam so stuck. what is the worked out answer for this question?

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

2x minus y equals 6, x plus y equals negative 3