Which method is used to solve systems of equations by substituting one variable?

The method used to solve systems of equations by substituting one variable is the Substitution Method. This approach involves isolating one variable in one of the equations and then substituting this expression into the other equation. By doing this, you can reduce the number of variables and solve for one variable directly. Once you have the value of one variable, you substitute it back into one of the original equations to find the value of the other variable. This method is particularly useful when one equation is already solved for one variable or can easily be manipulated to do so. The substitution method offers a straightforward way to tackle systems of equations, highlighting the relationship between the variables involved.