How to make method that turns number grades into letter grades in Java <p>I am trying to write a method in Java that turns number grades into letter grades, but there is an error with the returns that I do not understand why. Any input would be appreciated.</p> <pre><code>import java.util.*; import static java.lang.System.out; public class Lab26 { public static void main(String[] args) { } public static String letterGrade(double grade) { String a = "A"; String b = "B"; String c = "C"; String d = "D"; String f = "F"; if (grade &lt;= 100 &amp;&amp; grade &gt;= 90) { return a; } else if (grade &lt; 90 &amp;&amp; grade &gt;= 80) { return b; } else if (grade &lt; 80 &amp;&amp; grade &gt;= 70) { return c; } else if (grade &lt; 70 &amp;&amp; grade &gt;= 60) { return d; } else if (grade &lt; 60) { return f; } } } </code></pre>