Generate Grading in PHP by simple function

<?php

function makeGrade($score) {
    if($score>=80)
        return 'A+';
    if($score>=70)
        return 'A';
    if($score>=60)
        return 'A-';
    if($score>=50)
        return 'B';
    if($score>=40)
        return 'C';
    if($score>=33)
        return 'D';

    return 'F';
}

echo makeGrade( 80 ); //generate grade
echo "<br />\n";
echo makeGrade( 70 );//generate grade
echo "<br />\n";
echo makeGrade( 60 );//generate grade
echo "<br />\n";
echo makeGrade( 50 );//generate grade
echo "<br />\n";
echo makeGrade( 40 );//generate grade
echo "<br />\n";
echo makeGrade( 33 );//generate grade
echo "<br />\n";
echo makeGrade( 30 );//generate grade
echo "<br />\n";