Math: the systematic treatment of magnitude, relationships between figures and forms, and relations between quantities expressed symbolically.
Also, mathematical procedures, operations, or properties.
The letter “x” is often used in algebra to mean a value that is not yet known.
It is called a “variable” or sometimes an “unknown”.
The line on a graph that runs horizontally (left-right) through zero.
It is used as a reference line so you can measure from it.
The horizontal value in a pair of coordinates: how far along the point is.