Find the value of x.

The sum of all angles in a triangle is always 180°. Our triangle has 2 equal angles and one 40° angle. That means that the size of those two angles is (180° - 40° ) / 2 = 70°. Then from 180° or half circle subtract 70° and you will end up with 110° which the value of x.
Hope this helps.
r3t40
The two angles other than 40° in the triangle are same so let us name it y.
Now, sum of interior angles of a triangle is 180°
Therefore,
40 + y + y = 180
40 + 2y = 180
2y = 180 - 40
2y = 140
y = 140/2
y = 70
Now x = 180 - y ( linear pair )
x = 180 - 70
x = 110°