text: ## DESCRIPTION
  ## 
  ## ENDDESCRIPTION
  
  
  ## DBsubject(Algebra)
  ## DBchapter(Absolute value expressions and functions)
  ## DBsection(Absolute value inequalities)
  ## Date(06/02/2017)
  ## Institution(Red Rocks Community College, Colorado Community College System)
  ## Author(Brenda Forland)
  ## MO(1)
  ## KEYWORDS('college algebra','absolute value')
  
  
  #######################################
  #  Initialization
  
  
  DOCUMENT();  
  
  loadMacros(
  "PGstandard.pl",
  "MathObjects.pl",
  "AnswerFormatHelp.pl",
  "PGML.pl",
  "PGchoicemacros.pl",
  "PGcourse.pl",
  );
  
  TEXT(beginproblem());
  
  ###########################
  #  Setup
  $a = random(1,9,1);
  do { $b = random(-9,9,1); } until ( $b != $a );
  
  $ans1=Interval("($b-$a, $b+$a)");
  
  $mc = new_checkbox_multiple_choice();
  $mc -> qa (
  "In absolute value notation, where \( x \) represents the numbers, this is:", 
  "\( |x-$b| < $a \)$BR",                
  );
  $mc -> extra(
  "\( |x-$b| > $a \)$BR",
  "\( |x-$a| < $b \)$BR",
  "\( |x-$a| > $b \)$BR",
  );
  $mc -> makeLast("None of the above");
  
  
  ###########################
  #  Main text
  
  BEGIN_TEXT
  Find the interval(s) of numbers that are less than a distance of \( $a \) from \( $b \). Enter solution as an interval or union of intervals. 
  $BR
  $BR
  \{ ans_rule(20) \}
  \{ AnswerFormatHelp("intervals") \}
  $BR
  $BR
  \{ $mc -> print_q() \}
  $BR
  \{ $mc -> print_a() \}
  END_TEXT
  
  ############################
  #  Answer evaluation
  
  install_problem_grader(~~&std_problem_grader);
  
  $showPartialCorrectAnswers = 1;
  
  ANS($ans1->cmp());
  ANS( checkbox_cmp( $mc->correct_ans() ) );
  ############################
  #  Solution
  
  #BEGIN_PGML_SOLUTION
  #Solution explanation goes here.
  #END_PGML_SOLUTION
  
  COMMENT('Uses PGML.');
  
  ENDDOCUMENT();