It is the coefficient of the variable
That is often called the coefficient.
It is the coefficient of the unknown variable
It is called the coefficient of the variable
The coefficient would be the number multiplied by the variable, in this case: 7
(x - 25)*4
The number is called the coefficient of the variable
Variable is any letter used in an algebraic expression, and can vary (change form) to be any number, and one variable means the same number in any single algebraic expression. Usually algebra is simplifying the expression or equation until you know what the variable is equal to.
Let the number be x and so the expression is 8x