diff --git a/solution.py b/solution.py
index 2d7c775..cbf5977 100755
--- a/solution.py
+++ b/solution.py
@@ -6,9 +6,8 @@
 
 def predict(data):
     """ get two colums from `df` and returns the predicted ouput as a column (pd.Series)
-    TODO: modify it
     """
-    result = data['col1'] - data['col2']
+    result = data['col1'] + data['col2']
     return result