function getGrade(score) {
            let grade;
            (25 < score && score <= 30) ? grade = "A" :
            (20 < score && score <= 25) ? grade = "B" :
            (15 < score && score <= 20) ? grade = "C" :
            (10 < score && score <= 15) ? grade = "D" :
            (5 < score && score <= 10) ? grade = "E" :
            (0 <= score && score <= 5) ? grade = "F" :
            false
            return grade;
        }