In algebra, what is a value of a variable called if it makes an equation a true statement when substituted in?

1. The definition names the value that makes an equation a true statement, once substituted in, a solution. 2. A constant is a fixed number appearing in the equation, not a value found by solving it. 3. An expression or a coefficient can appear inside the equation, but neither word describes the value being sought. _Source: OpenStax Elementary Algebra (CC BY 4.0), Ch 2 "Solving Linear Equations and Inequalities", section 2.1 Solve Equations Using the Subtraction and Addition Properties of Equality_