aidez moi svp je galère :(

bonjour,
1)
angle ECD
angle ECD=angleACD-angleACE
angle ECD=180°-124°
angle ECD=56°
2)
angle EDC
angle EDC=angle BDC-angleEDB
angle EDC=180°-133°
angle EDC=47°
3)
triangle ECD
angle ECD+angle CDE+angle DEC=180°
56°+47°+angle CED=180°
103°+angle CED=180°
angleCED=180°-103°
angle  CED = 77°