diff --git a/core.py b/core.py
index 3c57548..6113320 100644
--- a/core.py
+++ b/core.py
@@ -1,3 +1,8 @@
 def add(x, y, z=0):
     """Add two (or three) objects"""
-    return x + y + z
\ No newline at end of file
+    return x + y + z
+
+
+def subtract(x, y):
+    """Subtract x from y"""
+    return x-y