A factory provides rides for its employees in either taxis or company cars. Each taxi ride can take 2 employees while each company car ride can take 3 employees. Since buying and maintaining cars is expensive, at most 60% of the rides can be company car rides. However, there has to be at least 30 company car rides. If the company needs to transport at least 500 employees, how many rides of each should be done to minimize the total number of taxi rides.