Very fun book especially for high school kids who like challenging algebra-type problems. For most people including myself, it requires a solid background of Algebra 2 to enjoy. The math typesetting used back in those days is distinctive and rather pleasing.
Since this book was first published in the late 1800s in the United Kingdom, it is in the public domain now. You can get it as a free ebook from Google Play.
The word algebra comes from the Arabic الجبر (al-jabr lit. "the reunion of broken parts") from the title of the book Ilm al-jabr wa'l-muḳābala by the Persian mathematician and astronomer al-Khwarizmi. The word entered the English language during the fifteenth century, from either Spanish, Italian, or Medieval Latin. It originally referred to the surgical procedure of setting broken or dislocated bones. The mathematical meaning was first recorded in the sixteenth century.