140 is 70% of what number in a proportion

Place the following steps in order to complete the square and solve the quadratic equation,

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

Hannah paid $3.20 for 16 ounces of potato chips. hank paid $3.23 for 17 ounces of potato chips. who paid less per ounces?