The cost of a charter flight to Miami is $225 each for 75 passengers, with a refund of $5 per passenger for each passenger in excess of 75. How many passengers must take the flight to produce a revenue of $15,580? Suppose x represents the number of passengers in excess of 75.if a refund of $5 per passenger for each passenger in 75 is given, find the refund if there are x passenger in excess of 75.