I have this part of my question:
BEGIN_PGML
State sales tax [`y`] is directly proportional to retail price [`x`]. An item that sells for [$a] dollars has a sales tax of [$b] dollars. Find a mathematical model that gives the amount of sales tax [`y`] in terms of the retail price [`x`]
The equation is [`y`]= [_______________]{"$k*x"}
But I want students to write the answer y= number*x , I tried this, but did not work :
The equation is [_______________]{"y=$k*x"}
Probably this is what you are looking for: https://webwork.maa.org/wiki/EquationEvaluators
Note that this will also accept all equivalent equations to y=$k*x, for example
y/$k=x or (y+10)/$k=x+10/$k.
Thanks, Andras. Does this work with PGML?
Yes,
The equation is [__]{$eqn}{20}
If you would like to enforce that the form of the answer be `y=...` then you should look into parserAssignment.pl (https://webwork.maa.org/pod/pg/macros/parserAssignment.html). These objects must be in the form "variable = expression". You are assigning a formula to the variable on the left.
Thank you so much, Alex. Although I do not understand these packages, it worked :) thank you again. But I had another issue with Currency. Can not I use more than one Context ? since after adding
Context("Numeric")->variables->add(y=>'Real');
parser::Assignment->Allow;
I go an error from the " Currency" context. it is in bold .
DOCUMENT(); # This should be the first executable line in the problem.
loadMacros(
"PGstandard.pl", # Standard macros for PG language
"MathObjects.pl",
"PGML.pl",
"contextCurrency.pl",
"PGcourse.pl",
"parserImplicitEquation.pl",
"parserAssignment.pl",
);
TEXT(beginproblem());
Context("Currency");
$showPartialCorrectAnswers = 1;
Context("Numeric")->variables->add(y=>'Real');
parser::Assignment->Allow;
$n=random(1,10,1);
$b=random(1,20,1);
$c=random(50,500,1);
$a=$n*$b;
$k=$a/$b;
$d=Currency($k*$c);
$f = Formula("y=$k*x");
BEGIN_PGML
State sales tax [`y`] is directly proportional to retail price [`x`]. An item that sells for [$a] dollars has a sales tax of [$b] dollars. Find a mathematical model that gives the amount of sales tax [`y`] in terms of the retail price [`x`]
The equation is [_______________]{"$f"}
What is the sales tax on a [$c] dollars purchase?
The answer is [_______________]{$d}
END_PGML
ENDDOCUMENT(); # This should be the last executable line in the problem.
You may use multiple Contexts within the same problem, but the issue here is that the Context("Numeric") continues to apply until you declare a new Context. You will need to re-arrange your code so that you change the context to "Currency" (from "Numeric") before declaring your Currency variable.
TEXT(beginproblem());
$showPartialCorrectAnswers = 1;
Context("Numeric")->variables->add(y=>'Real');
parser::Assignment->Allow;
$n=random(1,10,1);
$b=random(1,20,1);
$c=random(50,500,1);
$a=$n*$b;
$k=$a/$b;
$f = Formula("y=$k*x");
Context("Currency");
$d=Currency($k*$c);
The equation is [_______________]{$f}
Thank you, Andrew. This is a very clear explanation.
> Where do I need to place TEXT(beginproblem()); ?
What I mean is, you do not need that line at all. It was in your sample code earlier and you can delete it.
Ohh, yes I understand now. Thank you again, Alex. I do have another off-topic question. How to find an " organized, structured, comprehensive tutorial of this PERL syntax
Personally, I like "Perl in 2 hours 30 minutes"
https://qntm.org/perl_en
Note that this is restricted to solely Perl syntax, and PG (the WeBWorK problem coding language) is built on top of Perl. You'll also want to read through the details of MathObjects (the OOPerl classes):
https://webwork.maa.org/wiki/Introduction_to_MathObjects
https://webwork.maa.org/wiki/Introduction_to_Contexts
https://webwork.maa.org/wiki/Category:MathObject_Classes
https://webwork.maa.org/wiki/Common_MathObject_Methods
Thank you, Andrew. This should be sufficient :)