Consider an espresso stand with a single barista. Customers arrive to the stand at the rate of 28 per hour according to a Poisson distribution. Service times are exponentially distributed with a service rate of 35 customers per hour. If the arrival rate remains at 28 customers per hour and the stand's manager wants to have the average time a customer spends in the system (i.e., wait time + service time) to be a maximum of 5 minutes on average, then the service rate must become WHAT per hour? Enter your answer to WHAT as a rate served per hour.