Linear Equations: The Basics

An equation is two things that are equal, with an equals sign between them. A variable is a letter that stands for a number you do not know yet, and it is usually $x$. Solving means getting $x$ alone on one side so you can read the answer.

There is one rule: whatever you do to one side, do the same thing to the other side. To get $x$ alone, undo what is being done to it. Undo adding by subtracting, and undo multiplying by dividing. Handle adding and subtracting first, then multiplying and dividing.

Inequalities use the signs greater than, less than, or the versions with a line underneath. You solve them the same way. The only extra rule is this: if you multiply or divide both sides by a negative number, flip the direction of the sign.

Always put your answer back into the original problem to check it.