Sau 18 tháng, số tiền nợ cả gốc lẫn lãi phải trả là $5200. Số tiền gốc là bao nhiêu nếu lãi suất đơn là 8%/năm?

Ineed i been stuck on this question since yesterday

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

Lola says these two expressions have the same value. expression a expression b which explains whether lola is correct?