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.