diff --git a/chapter06.tex b/chapter06.tex
index b021f93..c6438ed 100644
--- a/chapter06.tex
+++ b/chapter06.tex
@@ -25,7 +25,7 @@ a greedy algorithm works.
 
 As a first example, we consider a problem
 where we are given a set of coins
-and our task is to form a sum of money $s$
+and our task is to form a sum of money $x$
 using the coins.
 The values of the coins are
 $\{c_1,c_2,\ldots,c_k\}$,
@@ -34,7 +34,7 @@ What is the minimum number of coins needed?
 
 For example, if the coins are the euro coins (in cents)
 \[\{1,2,5,10,20,50,100,200\}\]
-and $s=520$,
+and $x=520$,
 we need at least four coins.
 The optimal solution is to select coins
 $200+200+100+20$ whose sum is 520.