diff --git a/cis237assignment3/IDroid.cs b/cis237assignment3/IDroid.cs
new file mode 100644
index 0000000000000000000000000000000000000000..f614a058a2434170f29046eca0fdcf88d2474468
--- /dev/null
+++ b/cis237assignment3/IDroid.cs
@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace cis237assignment3
+{
+    interface IDroid
+    {
+        void CalculateTotalCost();
+
+        decimal TotalCost { get; set; }
+    }
+}