In the figure lines 1, m, and n are parallel. a classmate says you can use the corollary to side-splitter theorem to find x. explain your classmates error.

You should not make that assumption in this problem.

The side-splitter theorem is about the line segments that are formed on the transverals themselves. It is not talking about the distances on the set of parallel lines. If you wanted to find the value of x, you should look for another way to prove the relationship involving the x-value.