Solution
We know that the sum of angles of a triangle are 180°
If you don't know how to find the angles of a triangle
We use the formula,

Where n replicates the sides of a polygon
Applying the sides into the formula we get

Now in order to find x we sum up all the angles into a equation
90°+ 65°+ x - 10° = 180°
145 + x = 180
We then transpose 145 to the Right Hand Side (RHS)
x = 180 - 145
x = 35°
Hence , the value of x is 35°