Question

What are variables? Why should I even use them instead of numbers and words?

Answer 1

A variable is a symbol that represent a quantity in an algebraic expression. A variable can take any value.The letters x, y, z etc are used to denote variables.

Example:

The length of sides of a triangle are variables, since the length of the sides can take different values. But, the number of sides in a triangle is constant(fixed), since every triangle has three sides.

Need for using variables:

Variables are very useful in generalising. For eg :
The equation
X+Y=6 is an equation having variables X and Y
This equation represents all those values of X and Y which satisfies the equation.
Where as
1+5=6 here there is no variable and hence this is a fixed equation.