It is stated in the problem that ΔGEO is congruent with ΔFUN. On the first triangle, the measurement of angle E and angle G is given but the measurement of angle O is not given. Using the congruence relation of the two triangles, it is true that

The measurement of angle N is provided in the problem, which is equal to 40 degrees. Hence, we can say that angle O has also an angle measurement of 40 degrees base on the statement above.
The sum of the interior angles of the triangle is equal to 180 degrees. This means that if we add up the interior angles of the triangle GEO, we have the following equation

Substitute the measurement of each angle on the equation above and compute, we get

Therefore, the value of x is equal to 20 degrees.