You might want to take a look at Algebrator. I bought it some time back to help me with my Intermediate algebra course and I can say that it was a wise decision. There are so many demos provided which you can browse through. You can also try out the questions related to ratios and adding fractions by just typing them in. Algebrator provides complete description to the problems which helps to make difficult concepts understandable . I would say that this program is absolutely the best that money can buy.
Algebrator is a very simple software and is certainly worth a try. You will find lot of interesting stuff there. I use it as reference software for my math problems and can swear that it has made learning math much more enjoyable.