--- sample.rb
+++ sample.rb
@@ -2,7 +2,13 @@
   a + b
 end
 
+def sub(a, b)
+  a - b
+end
+
 if __FILE__ == $0
   result = add(3, 5)
   puts "Three plus five is #{ result }"
+  result = sub(5, 3)
+  puts "five minus three is #{ result }"
 end
