Update README.md

Signed-off-by: Fabiana 🚀  Campanari <113218619+FabianaCampanari@users.noreply.github.com>

Author: FabianaCampanari

README.md

@@ -190,7 +190,9 @@ The **graphical method** for solving simple linear programming (LP) problems inv
 
 - **Decision Variables:** These are the variables that we want to determine the values of to optimize the ***[OBJECTIVE FUNCTION]()*** (e.g.) -
 
-### $\(x_1\)$ and $\(x_2\)$
+### $$\(x_1\)$$ and $$\(x_2\)$$
+
+<br>
 
 - **Objective Function:** This is the linear function that we aim to maximize or minimize. For example: