diff --git a/README.md b/README.md
index 8f5646f..33f638b 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,6 @@
 43 + 30 = 73
 53 / 8 = 6
 89 + 61 = 150
-13 - 20 = -7
 8 / 4 = 2
 37 - 75 = -38
 87 + 4 = 91