feat: Add Expression class to calculate area of a triangle using user input

Add a program that:
- Takes base and height as floating-point inputs from the user
- Calculates the area using the formula (base × height) / 2
- Outputs the computed area
- Demonstrates the use of arithmetic expressions and `Scanner` class for input.

Author: Someshdiwan

Section5OperatorExpression/src/Expression.java

@@ -2,19 +2,18 @@
 import java.util.Scanner;
 
 class Expression {
-    public static void main(String args[])
-    {
+    public static void main(String args[]) {
         float base;
         float height;
         float area;
 
-        System.out.println("Enter Base and Height ");
-        Scanner sc = new Scanner(System.in); //Read the value
+        Scanner sc = new Scanner(System.in);
+        System.out.println("Enter Base and Height: ");
 
         base = sc.nextFloat();
         height = sc.nextFloat();
 
         area = base * height / 2;
         System.out.println("Area of Triangle is " + area);
     }
-}
+}