The term for replacing a variable with another value or expression is "substitution."
Evaluating the expression.
That is called 'solving'.
It is called evaluating the equation.
Because you are substituting a number for a variable. Like substituting salt for sugar in a cake recipe. Although you really shouldn't do the latter.
The number is called the coefficient of the variable
That looks like the description of an EXPRESSION. However, an expression need not have "at least one operation"; a single number, or variable, is a perfectly valid expression.
A variable is a letter that represents a number. An expression that contains at least one variable is called variable expression, also called algebraic expression. A variable expression has one or more terms. A term is a number, a variable, or a product of numbers and variables. For example,3(x^2)y + 2xy + x - 7 is a variable expression, where you have 4 terms.When working with variable expression, you often use the substitution principle:If a = b, then a may be replaced by b in any expression.The set of numbers that a variable may be represent is called replacement set, or domain, of the variable. To evaluate a variable expression, you replace each variable with one of its values and simplify the numerical expression that results.Example: Evaluate the expression 2x - 4y for x = 5 and y = -9.Solution:2x - 4y= 2(5) - 4(-9)= 10 + 36=46
It is the coefficient of the variable
By replacing a number for the variable.