Write a function drivingcost() with input parameters drivenmiles, milespergallon, and dollarspergallon, that returns the dollar cost to drive those miles. all items are of type double. if the function is called with 50 20.0 3.1599, the function returns 7.89975. define that function in a program whose inputs are the car's miles/gallon and the gas dollars/gallon (both doubles). output the gas cost for 10 miles, 50 miles, and 400 miles, by calling your drivingcost function three times. output each floating-point value with two digits after the decimal point, which can be achieved by executing cout < < fixed < < setprecision(2); once before all other cout statements.

// program in C++.

#include <bits/stdc++.h>

using namespace std;

// function to calculate cost

double DrivingCost(double drivenMiles, double milesPerGallon, double dollarsPerGallon){

  double cost;

  //Expression to compute cost

  cost = drivenMiles / milesPerGallon * dollarsPerGallon;

  return cost;

}

// main function

int main()

{

   double drivenMiles, milesPerGallon, dollarsPerGallon;

  //initialise the variables

  drivenMiles = 50;

  milesPerGallon = 20.0;

  dollarsPerGallon = 3.1599;

  //Call function

  double cost = DrivingCost(drivenMiles,milesPerGallon,dollarsPerGallon);

  //Display result

  cout<<"Driven miles : "<<drivenMiles<<endl;

  cout<<"Miles per Gallon : "<<milesPerGallon<<endl;

  cout<<"Dollars per Gallon : "<<dollarsPerGallon<<endl;

  cout << fixed << setprecision(2);

  cout<<"The total driving cost : "<<cost ;

  return 0;

}

Explanation:

Declare and initialize drivenMiles with 50, milesPerGallon with 20.0 and dollarsPerGallon with 3.1599.Call the function DrivingCost() with these parameters,This will calculate the cost and return the value.Print the result after getting the cost.Similarly we can calculate cost for drivenMiles equals to 10 and 400 miles also.

Output:

Driven miles : 50

Miles per Gallon : 20

Dollars per Gallon : 3.1599

The total driving cost : 7.90