activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/counter"
        android:layout_width="40dp"
        android:layout_height="40dp"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="10dp"
        android:layout_marginTop="10dp"
        android:text="30"
        android:textSize="30sp"
        />

    <TextView
        android:id="@+id/score"
        android:layout_width="49dp"
        android:layout_height="40dp"
        android:layout_alignParentEnd="true"
        android:layout_alignParentTop="true"
        android:layout_marginRight="10dp"
        android:layout_marginTop="10dp"
        android:text="0/30"
        android:textSize="30sp"
        />

    <Button
        android:id="@+id/playButton"
        style="@style/Widget.AppCompat.Button.Colored"
        android:layout_width="wrap_content"

        android:layout_height="wrap_content"
        android:layout_below="@+id/answerCheck"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="58dp"
        android:onClick="playFunc"
        android:text="Play" />

    <TextView
        android:id="@+id/answerCheck"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignStart="@+id/gridView"
        android:layout_below="@+id/gridView"
        android:layout_marginTop="28dp"
        android:text="Correct Answer"
        android:textSize="24sp" />

    <GridLayout
        android:id="@+id/gridView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:columnCount="2"
        android:rowCount="2"
        android:layout_below="@+id/score"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="102dp">

        <Button
            android:id="@+id/button"
            style="@style/Widget.AppCompat.Button.Borderless.Colored"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="17+2"
            android:textSize="18sp" />

        <Button
            android:id="@+id/button2"
            style="@style/Widget.AppCompat.Button.Borderless.Colored"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="19-4"
            android:textSize="18sp" />

        <Button
            android:id="@+id/button3"
            style="@style/Widget.AppCompat.Button.Borderless.Colored"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="20-6"
            android:textSize="18sp" />

        <Button
            android:id="@+id/button5"
            style="@style/Widget.AppCompat.Button.Borderless.Colored"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="12+6"
            android:textSize="18sp" />
    </GridLayout>

    <TextView
        android:id="@+id/questionText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/counter"
        android:layout_marginTop="27dp"
        android:text="        Click on Play to Play!!"
        android:textSize="30sp" />
</RelativeLayout>

mainactivity.java

package me.mukundmadhav.braintrainerapp;

import android.os.CountDownTimer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.GridLayout;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    //Defining   Components
    GridLayout grid;
    TextView counter,score,correctAnswerCheck,question;


    public void playFunc(View view){


        //set visiblity
        question.setText("What is 1.5*2*5 ?");
        score.setVisibility(View.VISIBLE);
        grid.setVisibility(View.VISIBLE);
        counter.setVisibility(View.VISIBLE);

        new CountDownTimer(10000, 1000) {
            @Override
            public void onTick(long millisUntilFinished) {
                counter.setText(String.valueOf(millisUntilFinished));
            }

            @Override
            public void onFinish() {

            }
        };

        //set Play Invisble
        Button playButton = (Button) findViewById(R.id.playButton);
        playButton.setVisibility(View.INVISIBLE);

    }


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

        //Assigning Values
        counter=(TextView) findViewById(R.id.counter);
        score=(TextView) findViewById(R.id.score);
        correctAnswerCheck=(TextView) findViewById(R.id.answerCheck);
        grid = (GridLayout) findViewById(R.id.gridView);
        question=(TextView) findViewById(R.id.questionText);

        //Set View as invisble
        counter.setVisibility(View.INVISIBLE);
        score.setVisibility(View.INVISIBLE);
        correctAnswerCheck.setVisibility(View.INVISIBLE);
        grid.setVisibility(View.INVISIBLE);
    }
}