Question

ABCD is a quadrilateral with angle BAD=40
AB is extended to E and angle EBC=30
AB=AD and BC=BD
Calculate angle BCD

Answer 1

here AB=AD

so ANGLE ABD=ADB=x

x+x+40=180

2x=140

x=70

so CBD=180-30-70=80

and BD=BC

so angle BDC=BCD=y

and in∆BCD

y+y+80=180

2y=100
y=50

Answer 2

here's your answer reasons given in brackets in short