Jefferson High School is looking to expand its students parking lot by expanding the existing lot as shown below. The size of the new parking lot will be twice the size of the old parking lot. How many feet, x, was the old parking lot expanded by?

It's like discovering the answer to a puzzle. the purpose in solving an equation is to find the value or values of the variable that makes it a true statement. any value of the variable that makes the equation true is called a solution to the equation.