100 Things: #35
Ever wonder why we always solve for X in algebra? Well, it's because algebra was invented in the Middle East, and the character that equations solved for was, roughly, "sh". This sound is a single character in Arabic. When algebra entered Europe through Moorish Spain, Arabic characters were changed to Spanish characters, and in Spanish there is no single character for "sh". So, X was substituted. That's why we always solve for X.