Update 20-object-oriented-programming.md

Author: parewa-ranjit

20-object-oriented-programming.md

@@ -338,8 +338,8 @@ class Triangle:
         self.c = c
 
     def get_perimeter(self):
-        p = self.a + self.b + self.c
-        return p
+        perimeter = self.a + self.b + self.c
+        return perimeter
 
 t1 = Triangle(3, 4, 5)
 
@@ -350,4 +350,4 @@ print("The perimeter of the triangle is", perimeter)
 **Output**
 ```
 The perimeter of the triangle is 12
-```
+```