American income tax calculator/ Enter relationship status( married or not) and your income,

#include <iostream>
#include <string>
using namespace std;

void tax(string answer, int inc)
{
    double tax = 0;
    if (answer == "Yes" || answer == "yes")
    {
        //single
        if (inc > 0 && inc <= 21400)
        {
            tax = inc * 0.15;
            cout << tax;
        }
        else if (inc >21450 && inc <= 51900)
        {
            tax = 3217.50 + (inc- 21450.00) * 0.28;
            cout << tax;
        }
        else if (inc > 51900)
        {
            tax = 11743.00 + (inc - 51900.00) * 0.31;
            cout << tax;
        }
        else
        {
            cout << "Incorrect income value. Try again.";
        }
    }
    else if (answer == "No" || answer == "no")
    {
        //married
        if (inc > 0 && inc <= 35800)
        {
            tax = inc * 0.15;
            cout << tax;
        }
        else if (inc > 35800 && inc <= 86500)
        {
            tax = 5370.00 + (inc - 35800.00) * 0.28;
            cout << tax;
        }
        else if (inc > 86500)
        {
            tax = 19566.00 + (inc - 86500.00) * 0.31;
            cout << tax;
        }
        else
        {
            cout << "Incorrect income value. Try again.";
        }
    }
    else
    {
        cout << "Incorrect relationship status. Try again.";
    }
}

int main()
{
    string answer;
    int inc;
    cout << "Are you single? \n";
    cin >> answer;
    cout << "What is your income? \n";
    cin >> inc;
    cout << "Your tax is: $";
    tax(answer, inc);
    return 0;
}