diff --git a/education/software development/ECE1400/Chapter 15 Exercises.md b/education/software development/ECE1400/Chapter 15 Exercises.md
index cbd6ac6..41822ad 100644
--- a/education/software development/ECE1400/Chapter 15 Exercises.md	
+++ b/education/software development/ECE1400/Chapter 15 Exercises.md	
@@ -39,4 +39,13 @@ When `DEBUG` is defined, any instances of the `PRINT_DEBUG` token are replaced w
 
 > (d). Is it necessary for the `DEBUG` macro to be defined *before* `debug.h` is included in order for `PRINT_DEBUG` to have the desired effect? Justify your answer.
 
-Macro invocations are evaluated sequentially, and so if `DEBUG` was defined after `PRINT_DEBUG`, then any usages of `PRINT_EVALUATION` would be have like `DEBUG` was not defined.
\ No newline at end of file
+Macro invocations are evaluated sequentially, and so if `DEBUG` was defined after `PRINT_DEBUG`, then any usages of `PRINT_EVALUATION` would be have like `DEBUG` was not defined.
+
+---
+
+> **5.** Suppose that a program consists of three source files - `main.c`, `f1.c`, and `f2.c`- Plus two header files, `f1.h` and `f2.h`. All three source files include `f1.h` but only `f1.c` and `f2.c` include `f2.h`. Write a makefile for this program, assuming that the compiler is `gcc` and that the executable file is to be named `demo`.
+
+---
+
+> **6.** The following questions refer to the program described in Exercise 5.
+> (a). Wh