👉 In mathematics, a pro-substitution is a type of substitution in which one variable is replaced by another variable. This can be done to simplify an expression or equation. For example, if you have an equation like x + y = 5 and you want to find the value of x, you would use a pro-substitution to replace y with x. The term "prosubstitution" is used in algebra where it refers to an operation that makes one variable disappear while keeping the other variable unchanged
