This one is very simple.
The triangle on the left has two equal sides, so the angle on the opposite side of that same triangle is also 52º. That angle is on a 180º line, so the angle right next to it has to be 180º - 52º, so 128º. The other two angles of that triangle are unknown, but still equal because of the sides being the same. So, subtract 128º from 180º to get 52º again, but divide it by two. The angle measurement of x = 26º
