A large office has been having breakdown problems with one of its copy machines. Over the past $20$ weeks, the machine has broken down as indicated below. Each time the copier breaks$$ down, the firm loses an average of$$ $$500$ in time and repair expenses. If preventive maintenance were$$ implemented, it is estimated that the copier will breakdowns per week would occur$).$The cost of preventive maintenance is $$190$ per week.