Let's consider what the question asks for:
--> find the value of 'x'
The function gives us a quadrilateral
--> separated into two triangles
In the triangle that has one angle with measure 65 degrees
-->it is an isosceles triangle thus the top most angle in that triangle is also
65 degrees
--> the other unknown angle is, therefore:

Now that unknown angle forms a complementary relationship with the angle of the other triangle.

Now that the bottom triangle
--> has an angle with measure 'x'
--> that triangle is also an isosceles
--> meaning that our triangle's angle looks like this

Answer: 70