The triangle is isosceles so the other two angles are the same.
Since all the angles in a triangle add up to $180^\circ$ then those angles are $70^\circ$ each. Now, $x$ is the suplementary angle to one of them i.e. $70^\circ + x = 180^\circ$ therefore $x = 110^\circ$
The triangle is isosceles so the other two angles are the same.
Since all the angles in a triangle add up to $180^\circ$ then those angles are $70^\circ$ each. Now, $x$ is the suplementary angle to one of them i.e. $70^\circ + x = 180^\circ$ therefore $x = 110^\circ$