diff --git a/education/software development/ECE1400/Chapter 9 Exercises.md b/education/software development/ECE1400/Chapter 9 Exercises.md
index ebc3876..e01a084 100644
--- a/education/software development/ECE1400/Chapter 9 Exercises.md	
+++ b/education/software development/ECE1400/Chapter 9 Exercises.md	
@@ -50,18 +50,29 @@ Parameters must contain a type annotation but they do not need to specify a name
 
 > 9. What will be the output of the following program?
 ```c
-double triangle_area(double base, double height)
+#include <stdio.h>
+
+void swap (int a, int b);
+
+int main(void)
 {
-	double product;
-	product = base * height;
-	return product / 2;
+    int i = 1, j = 2;
+    swap(i, j);
+    printf("i = %d, j = %d\n", i, j);
+    return 0;
 }
-double triangle_area(double base, double height)
+
+void swap(int a, int b)
 {
-	double product;
-	product = base * height;
-	return product / 2;
+    int temp = a;
+    a = b;
+    b = temp;
 }
 
 ```
 
+Answer:
+```
+i = 1, j = 2
+```
+Because function parameters are passed by value and not reference in C, modifications to `a` and `b` are limited to the scope of `swap`. 
\ No newline at end of file