The letter 
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 ‘ ‘, it may be ‘ 
‘, ‘ 
‘ ,’ 
‘ 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:
subtracting ‘9’ on both sides
