option b. there is 2 possibilities
1. thr is two 80 degrees angle in wxy (80 degrees is the base angle of an isosceles triangle)
2.thr is one 80 degree angle in wxy and the remaining 2 angles are equal
if we use scenerio 1 , the angle would be 180-(80×2)=20
if we use scenerio 2, the angle would be (180-80)÷2=50,but 50 is not in any of the option hence the answer is 20