Can someone help to get a better understanding of how to solve this questions and others like this?

Since one angle is  50°, then   x  = [ 180 - 50  ]  / 2  =   130  / 2   = 65°

Since two angles  = x, then these angles are equal

The triangle is

(a) acute  -  all angle are  < 90°

(b) isosceles -  two angles are equal, therefore the two sides opposite them are equal