X is definitely the most common variable. Some people use Y too.
The letter x.
The letter x.
x
a variable
In the expression 6n+3 the variable or the unknown is n
The letter x.
The letter x.
x
x
variable is the unknown number. usually represented as a letter
It is a variable
a variable
A variable.
In the expression 6n+3 the variable or the unknown is n
it is called a variable not a letter
It is a variable
In math a letter is a variable and it can be any number.