Best way to transfer variables from one activity to the next in Android?

package ericleeconklin.costoflivingcalculator;

import android.app.Application;
import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import java.lang.Double;


public class EnterIncome extends ActionBarActivity {

    public Double myIncome;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_enter_income);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_enter_income, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public class myVariables extends Application {

        private Double income;

        public Double getIncome() {
            return income;
        }

        public void setIncome(Double income) {
            this.income = income;
        }

        private Double rentMortgage;

        public Double getrentMortgage() {
            return rentMortgage;
        }

        public void setrentMortgage(Double rentMortgage) {
            this.rentMortgage = rentMortgage;
        }

        private Double insurance;

        public Double getinsurance() {
            return insurance;
        }

        public void setinsurance(Double insurance) {
            this.insurance = insurance;
        }

        private Double utilities;

        public Double getutilities() {
            return utilities;
        }

        public void setutilities(Double utilities) {
            this.utilities = utilities;
        }

        private Double phoneInternet;

        public Double getphoneInternet() {
            return phoneInternet;
        }

        public void setphoneInternet(Double phoneInternet) {
            this.phoneInternet = phoneInternet;
        }

        private Double food;

        public Double getfood() {
            return food;
        }

        public void setfood(Double food) {
            this.food = food;
        }

        private Double carPayment;

        public Double getcarPayment() {
            return carPayment;
        }

        public void setcarPayment(Double carPayment) {
            this.carPayment = carPayment;
        }

        private Double misc;

        public Double getmisc() {
            return misc;
        }

        public void setmisc(Double misc) {
            this.misc = misc;
        }
    }

    public void getIncome(View view){
        String myIncomeString;
        TextView incomeView = (TextView)findViewById(R.id.enterIncome);
        myIncomeString = incomeView.getText().toString();
        myIncome = Double.parseDouble(myIncomeString);
        ((myVariables) this.getApplication()).setIncome(myIncome);
        Intent myIntent = new Intent(this, EnterExpenses.class);
        startActivity(myIntent);
    }

}