diff --git a/education/software development/ECE1400/Chapter 4 Exercises.md b/education/software development/ECE1400/Chapter 4 Exercises.md
index 015109d..bc7819a 100644
--- a/education/software development/ECE1400/Chapter 4 Exercises.md	
+++ b/education/software development/ECE1400/Chapter 4 Exercises.md	
@@ -4,9 +4,13 @@ b. `0`
 c. `1`
 d. `0`
 # 3.
-a. `1`, `2`
-b. 
+a. `1`
+b. `-1`, `-2`
+c. `-1`, `-1`
+d. `1`, `2`
 
 # 9.
+
+
 # 11.
 # 15.