$48.$ The company must replace its aging machinery with better, but much more expensive, machines. In addition, raw material prices increase, so that monthly costs go up by $$250,000.$ Owing to competitive pressure, phone prices cannot be increased, so revenue remains the same. Under these new circumstances, fi nd the approximate profi t from manufacturing the given number of phones. $($a$)20,000($b$)36,000($c$)40,000$