diff --git a/education/software development/ECE1400/Chapter 15 Exercises.md b/education/software development/ECE1400/Chapter 15 Exercises.md
index 0b141db..9b95c45 100644
--- a/education/software development/ECE1400/Chapter 15 Exercises.md	
+++ b/education/software development/ECE1400/Chapter 15 Exercises.md	
@@ -51,7 +51,10 @@ Macro invocations are evaluated sequentially, and so if `DEBUG` was defined afte
 > **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`.
 ```makefile
 demo: main.o f1.o f2.o
+	gcc -o demo main.o f1.o f2.o
 
+main.o: main.c f1.h
+	gcc -c main.c
 
 ```
 ---