import {useState} from 'react';

import {View, Text, Button, TextInput} from 'react-native';

 function calculateGrade(marks)

  {

  var grade;

if( marks < 50 )

  grade="F";

else if(marks >= 50 && marks < 60)

  grade="E"

else if(marks >= 60 && marks < 70)

  grade="D"

else if(marks >= 70 && marks < 80)

  grade="C"

else if(marks >= 80 && marks < 90)

  grade="B"

  grade="A"

return grade;

  }

const App = ()=>{

  const [marks, setMarks] = useState();

  const [grade, setGrade] = useState();

 

  return(

    <View>

   

   

    <TextInput

    onChangeText={setMarks}

    style={{borderWidth:1, marginTop:10}} />

    <Button

    title="Calculate Grade"

    onPress={ () => setGrade( calculateGrade(marks) )}

     />

    <Text>Grade: {grade}</Text>

    </View>

  )

}

export default App;