A math class is having a discussion on how to determine if the expressions 4 x minus x + 5 and 8 minus 3 x minus 3 are equivalent using substitution. The class has suggested four different methods.

Which describes the correct method?
*Both expressions should be evaluated with one value. If the final values of the expressions are both positive, then the two expressions must be equivalent.
*Both expressions should be evaluated with one value. If the final values of the expressions are the same, then the two expressions must be equivalent.
*Both expressions should be evaluated with two different values. If for each substituted value, the final values of the expressions are positive, then the two expressions must be equivalent.
*Both expressions should be evaluated with two different values. If for each substituted value, the final values of the expressions are the same, then the two expressions must be equivalent.