Acertain number is multiplied by 3, and then 5 is added to the result. the final answer is 72. what is the number

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

With number 11 ( show how you got the answer)

Jack bought x picks costing $30 each and y shovels costing $40 each. in all he spent $240