I don’t think I know of any resource where you can get your solutions of houghton mifflin prep algebra checked within hours. There however are a couple of companies which do offer assistance, but one has to wait for at least 24 hours before getting some reply .What I know for sure is that, this program called Algebrator, that I used during my college career was really good and I was quite happy with it. It almost gives the type of results you need.
That's true, a good software can do miracles . I used a few but Algebrator is the greatest. It doesn't matter what class you are in, I myself used it in Algebra 1 and Intermediate algebra as well , so you don't have to worry that it's not on your level. If you never had a software until now I can tell you it's not hard , you don't have to know anything about the computer to use it. You just have to type in the keywords of the exercise, and then the program solves it step by step, so you get more than just the answer.
I remember having problems with graphing lines, complex fractions and rational inequalities. Algebrator is a truly great piece of math software. I have used it through several algebra classes - Intermediate algebra, Algebra 1 and Algebra 2. I would simply type in the problem and by clicking on Solve, step by step solution would appear. The program is highly recommended.