diff --git a/rulesOfDifferentiation/exercises/derivativeTangentLinesFromAPoint.tex b/rulesOfDifferentiation/exercises/derivativeTangentLinesFromAPoint.tex
index 90db40835..6322a00f4 100644
--- a/rulesOfDifferentiation/exercises/derivativeTangentLinesFromAPoint.tex
+++ b/rulesOfDifferentiation/exercises/derivativeTangentLinesFromAPoint.tex
@@ -82,7 +82,7 @@
 \]
 and, expressing $f'(a)$ in terms of $a$, we obtain that
 \[
- m= \answer{-2}a.\\
+ m= \answer{-2} a.\\
  \]