The letter x is used in algebra (Math) to mean a value that is not yet known.

Sometimes we call it variable or unknown.

In x+2=9, x is variable but we can work out if we try!

A variable does not have to be ‘ x ‘, it may be ‘ y ‘, ‘ z ‘ ,’ w ‘ or any letter named or symbol.

The above question could be asked what does x means in math.

## Examples:1 what is x

Find the value of x, if x+9=4.

**Solution:**

x+9=4

subtracting ‘9’ on both sides

x+9-9=4-9

x+0=-5

x=-5