diff --git a/2-variables/quadratic-formula/quadratic.cpp b/2-variables/quadratic-formula/quadratic.cpp
index 6cb249e..7401e4a 100644
--- a/2-variables/quadratic-formula/quadratic.cpp
+++ b/2-variables/quadratic-formula/quadratic.cpp
@@ -1,26 +1,28 @@
-#include <iostream>
+// Quadratic formula 
+#include <iostream> 
 #include <cmath>
 
-int main() {
+int main(){
+  // 1. declare variable a,b,c
+  double a,b,c;
 
-  double a, b, c;
-  double root1, root2;
-
-  std::cout << "Enter a: ";
+  //2,3 Input a,b,c
+  std::cout << "Enter a : ";
   std::cin >> a;
 
-  std::cout << "Enter b: ";
+  std::cout << "Enter b : ";
   std::cin >> b;
 
-  std::cout << "Enter c: ";
+  std::cout << "Enter c : ";
   std::cin >> c;
 
+  // 4. declare two variable root1 and root2
+  double root1, root2;
+
+  // 5. formula of root1 
   root1 = (-b + std::sqrt(b*b - 4*a*c)) / (2*a);
   root2 = (-b - std::sqrt(b*b - 4*a*c)) / (2*a);
-
   std::cout << "Root 1 is " << root1 << "\n";
   std::cout << "Root 2 is " << root2 << "\n";
-
   return 0;
-  
 }