write a function named bestMileage()

we are starting with structures, streams and vectors. any help is appreciated

7 THE bestMileage PROBLEM Using the Car structure defined in file p1.cpp, taken from the 2017 EPA testing results, write the function named bestMileage(). The function takes one input parameter: a vector of Cars that represents the testing data. The vector is sorted by manufacturer, so all cars of a particular manufacturer are together in the vector. The function also has an output parameter, a vector of string that contains both the manufacturer and the model concatenated together, separated by a semicolon, like this: "BMW;430i Coupe" Each entry is the car with the best mileage from each manufacturer. The function returns the average mileage of the selected cars. vector