Update algebra.html

Signed-off-by: Coding331 <[email protected]>

Author: Coding331

algebra.html

@@ -101,7 +101,7 @@
         <h1>Algebra Study Guide</h1>
     </header>
     <nav>
-        <a href="index.html">Back to Study Guide</a>
+        <a href="math.html">Back to Study Guide</a>
         <a href="library.html">Library</a>
         <a href="notes.html">Notes</a>
         <a href="feedback.html">Feedback</a>