Update app.py

app.py

@@ -807,6 +807,7 @@ Your complete solution must:
 - Show every step of the calculation
 - Include all necessary verifications
 - Maintain proper LaTeX formatting with $ for inline math and $ on separate lines
+- When referring to the dollar as a currency, never use the `$` symbol but rather write out the word dollar
 
 Remember to write out the complete solution even if you only need to add a few steps - the goal is to have a single, complete, verified solution that includes everything necessary for full mathematical rigor.