Uses alternate method of obtaining HRW answers. This should work with all types of problems.

hrw-alternate.user.js

// ==UserScript==
// @name         My HRW Assistant (Plan B)
// @namespace    http://github.com/scoliono
// @version      1.1
// @description  Provides answers to HRW problems upon pressing "Viewer Help" button.
// @author       scoliono
// @match        https://my.hrw.com/wwtb/api/viewer.pl
// @grant        none
// ==/UserScript==

var answer_toggle_display = true;

bc_help = function() {
    if (answer_toggle_display == true)
    {
        $("#borders").after('<iframe width="700" height="250" style="border:none;" id="answers_container" src="https://my.hrw.com/wwtb/api/viewquestion.pl?qid='+cFLque.que.tid.split("chap").join("").split("sect").join("").split("prob").join("")+'&qtxt='+WFO.seed+'"></iframe>');
        answer_toggle_display = false;
    }
    else
    {
        $("#answers_container").remove();
        answer_toggle_display = true;
    }
};

var old_bc_next = bc_next;
var old_bc_jumpto = bc_jumpto;

bc_next = function() {
    old_bc_next();
    $("#answers_container").remove();
    answer_toggle_display = true;
};

bc_jumpto = function(cqn,checked) {
    old_bc_jumpto(cqn,checked);
    $("#answers_container").remove();
    answer_toggle_display = true;
};

As of 1/28/16, this also works on Assessment Readiness/Ready to Go On? assignments.

Version 1.1 - 2/15/16

• Now includes the assignment's seed in the request, so even if HRW randomizes the numbers in a question, the answer you receive accounts for this and should be correct all the time.