That depends ... on what X and Y are!
And if that does not come naturally to you, perhaps you should read The Complete Idiot's Guide to Pre-Algebra by Amy Szczepanski and Andrew Kositsky.
The CIG to PA is built just like the other books in the Idiot's series, using familiar conventions to keep the flow of the book smooth while providing additional ancillary information, and in the case of this text, practice problems (answers provided in the back). This book reminds me of a tired old reference I've got on my shelf called Technical Mathematics. Sometimes you just need a place to look up the formula for the volume of a cone.
I've compared the contents and methods of presentation of this book to the equivalent textbook Julia used in school last year (7th grade math = pre Algebra in Minnesota) and found the Idiot's guide to be simpler, more straightforward, less confusing as a book, and better presented. However, the textbook (which is pretty standard textbook) is much better designed to use in a math class. Our school district uses a technique called "spiral learning" in which the same topic is revisited again and again and again ... first introduced, then in depth, then reviewed, then reviewed again later on. This makes for a text that is hard to use if you want to go fast or just look something up, but it is great in a classroom setting where a teacher is working with a well designed syllabus and other materials.
But out of the traditional classroom, as summer reading so your kid can be smarter than the other kids, as a review before delving into HS or even College algebra, or as a home schooling book, the CIG for Pre-Algebra works very nicely and is highly recommended.
What is Pre-Algebra (so you know, whether this book fits your needs or not)? The definition of Pre-Algebra probably varies a bit from place to palce and time to time, but here's a rough list of topics:
Basic number theory ... remember all those different kinds of numbers, like "natural" and "whole" and "skimmed" (no, wait, "skimmed" is milk, not numbers).
Addition, subtraction, multiplication and division ... (so what, you say!!!) of not just numbers but of exponents, decimals, negative and positive terms, and exponents. Ultimately, these are many of the basic rules you will need in algebra.
Basic expressions ... what re they ... and introduction to equations.
Geometry (areas, volume, etc. etc.) including the beginning of triangles. (Triangles are not just shapes, but rather, the beginnings of some heavy concepts. I mean after all, a whole branch of math is named after them ... Trigonometry. There is a reason we've never heard of Squarometry!)
Basic data analysis: Collecting data, display and basic analysis, and probability.
I cannot promise you that this book matches exactly your local state standards for pre-algebra math, but my sense is that it would for almost all possible users.
That sounds like a fun read! I loved algebra, solving problems that have definite answers...bliss. Now I can't remember a lot of the rules around exponents and, er, triangles (and exponents ;)) and that's just sad.
When my sister was little, she'd ask us older folk to "make her plusses" (or "goes intos", etc.). We'd create pages and pages of problems and she'd go tuck into some corner and just be in numbers; the ultimate comfort, ending in self-satisfaction!
It's odd how well these books seem to sell considering that anyone seen reading one will immediately be labeled as a 'complete dummy/idiot'
I'm assuming that the associative and distributative properties were also covered. I find that understanding those has always been the bedrock of being able to quickly break down an algebra problem or even to quickly do arithmetic in my head.
And if you're a teenage girl whose in to teen magazines, I've heard the Math Doesn't Suck series doesn't suck. (Kiss My Math is the pre-algebra one.)
Wish I had this in middle school. I struggled with math. I still do. My dissertation statistical analysis has been kicking my behind.
Lots of kids will say, "What am I ever going to need this stuff for?" The algebra that I learned all those years ago in 7th and 8th grade is something that I still use nearly every day. I really appreciate the fact that Mr. Deagan, my 8th grade algebra teacher, made class fun as well as informative.
The trouble with pre-algebra is it's kind of a made-up little catch-all of a course. Most of that stuff (and probably the first few weeks of an Algebra I course) can be solved by good logic skills and mental math... which robs you of sound foundation in the symbol manipulation which is what you really need to learn to master higher math.
I think it is a good book for parents to have to prep in the summer when their kids are about to take pre-algebra.
As for the Complete Idiot's/Dummies series, I think they are invaluable for people that want to get the basics on a subject but don't have the time to study in detail.
I have an idea for a Complete Idiot's book, and a chapter outline that I am fleshing out to try to sell on banking for small businesses. There are people who really need it.