AE || BC
===》 DCB angle = DAE angle
AC /
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Thus :
DCB angle = x
And also we know that the submission of interior angles of any triangle must equals to 180 degrees so :
In BCD triangle :
B + C + D = 180
x + x + D = 180
D = 180 - 2x
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In the other hand we know that :
BDC angle + BDA angle = 180
because they make a straight line together so ;
180 - 2x + 50 = 180
- 2x = 180 - 230
- 2x = - 50
x = 25
And we're done...
Have a great time ♡