Fix bug 4667, improve wording

Author: gajennings

OpenProblemLibrary/PCC/BasicAlgebra/LinearInequalities/InequalityWordProblem20.pg

@@ -64,7 +64,7 @@ $multians = MultiAnswer($left, $comparitor, $right)->with(
       my ( $correct, $student, $self ) = @_;
       my ( $stuLeft, $stuComp, $stuRight ) = @{$student};
       my ( $corLeft, $corComp, $corRight ) = @{$correct};
-      my $stuExpr = $stuLeft - $stuRight;
+      my $stuExpr = Formula("$stuLeft - $stuRight");
       my $coeff = $stuExpr->D('x');
       if (!($coeff -> isConstant) or $coeff == Formula(0)){ return 0; }
       $stuExpr = $stuExpr/$coeff; 
@@ -85,19 +85,19 @@ TEXT(beginproblem());
 BEGIN_PGML
 
 [%Not using percentages to avoid confusion%]
-Your grade in a class is determined by the average of three test scores. You scored [`[$a]`] and [`[$b]`] on the first two tests. To earn at least [`[$m]`] for this course, how much do you have to score on the third test?
+Your grade in a class is determined by the average of three test scores. You scored [`[$a]`] and [`[$b]`] points on the first two tests. To get an average score of at least [`[$m]`] points on the three tests, how many points would you need on the third test?
 
-Let [`x`] be the score you will earn on the third test. Write an inequality to represent this situation. 
+Let [`x`] be your score on the third test. Write an inequality to express the requirement that your average score must be at least [`[$m]`]. 
 
-Your inequality has three parts, a left side, a right side, and a comparison operator in the middle: [`<`], [`>`], [`\leq`], [`\geq`], [`=`], or [`\neq`]. Enter these as *<*, *>*, *<=*, *>=*, *=*, and *!=*.
+Your inequality has three parts, a left side, a right side, and a comparison operator in the middle: [`<`], [`>`], [`\leq`], [`\geq`], [`=`], or [`\neq`].  To type the comparison operator, enter one of these symbols:  *<*, *>*, *<=*, *>=*, *=*, or *!=*.
 
 >> [__________]{$multians} [__]{$multians} [__________]{$multians} <<
 
-Solve this inequality. What is the minimum that you have to earn on the third test in order to earn a [`[$m]`] for the course? 
+Solve this inequality. What is the minimum score that you must earn on the third test to earn a [`[$m]`] average for the three tests? 
 
     [___________]{$ans2}
 
-You cannot score over [`100`] on the third test. Use interval notation to represent the range of scores you can earn on the third test in order to earn at least [`[$m]`] for this course.
+You cannot score over [`100`] on the third test. Use interval notation to represent the range of scores you could earn on the third test to average at least [`[$m]`] in this course.
 
     [______________]{$interval}