Android Studio displaying numbers and math actions

tv and tv2 should display an math algoritm writen in "if" statement. Can someone help me solve this problem? this should do display the math action in tv if ((b/100)*a)c and when button1 is clicked , else it should do d/((bc)/100) when button2 is clicked and displays it in tv2.

MainActivity.java:

package com.example.marek.przelicznikpaliw;

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.EditText;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

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

    public void onButtonClick(View v){
        //pola
        EditText a1 = (EditText) findViewById(R.id.cel);
        EditText b1 = (EditText) findViewById(R.id.pali);
        EditText c1 = (EditText) findViewById(R.id.litr);
        EditText d1 = (EditText) findViewById(R.id.koszt);

        // wynik
        TextView tv = (TextView) findViewById(R.id.wynikKoszt);
        TextView tv2 = (TextView) findViewById(R.id.wynikKilometry);

        float a,b,c,d,wynik;
        a = Float.parseFloat(a1.getText().toString());
        b = Float.parseFloat(b1.getText().toString());
        c = Float.parseFloat(c1.getText().toString());
        d = Float.parseFloat(d1.getText().toString());
        wynik = 0;
        if (v.getId() == R.id.button) {
            wynik = ((b / 100) * a)*c;
        } else if (v.getId() == R.id.button2) {
            wynik = d/((b * c) / 100);
        }
        tv.setText(wynik+"");
        tv2.setText(wynik+"");
    }

    @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_main, 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);
    }
}

activity_main.xml :

<LinearLayout xmlns:android="http://ift.tt/nIICcg"
    xmlns:tools="http://ift.tt/LrGmb4" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity"
    android:orientation="vertical"
    android:onClick="onButtonClick">
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/cel"
        android:hint="Ilosc km do celu to:"
        android:layout_centerHorizontal="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/pali"
        android:hint="Ile litrow pali na 100km"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/cel" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/litr"
        android:hint="Cena za litr"
        android:layout_below="@+id/pali"
        android:layout_centerHorizontal="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/button"
        android:layout_below="@+id/litr"
        android:layout_centerHorizontal="true"
        android:hint="Licz zlotowki"
        android:text="Licz koszty"
        android:clickable="true" />

    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/koszt"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"
        android:hint="Za ile zl zostalo zatankowane gaz/paliwo?" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Licz kilometry"
        android:id="@+id/button2"
        android:layout_below="@+id/koszt"
        android:layout_centerHorizontal="true"
        android:clickable="true" />

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="@string/emptystring"
        android:id="@+id/wynikKoszt"
        android:textIsSelectable="true" />

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="@string/emptystring"
        android:id="@+id/wynikKilometry" />
</LinearLayout>