B. Boo and The Equation.cpp

//B. Boo and The Equation
#include <iostream>
#include <iomanip>
using namespace std;

int main ()
{
    double a, b, c; cin >> a >> b >> c;
    cout << fixed <<setprecision(6) <<(2*a + 3*b)* 5*c;

    return 0;
}