Answer:

Explanation:
Notice that since segments AB and DE are parallel, then angles
and
must be equal since they are alternate angles in between parallel lines.
So,
. We also know that
, then the remaining angle (
) in triangle CDE must be such that added to the other two angles results in
. That is:

Now, since angle D equals 10 times x, we can solve for the unknown x in the equation:
