∵∠ABC=100°
∴∠A+∠C=80°
∵AE=ED
∴∠A=∠ADE
∵BD=BC
∴∠BDC=∠C
∵∠ADE+∠BDC=80°
∴∠EDB=100°
∵ED=BD
∴∠DEB=∠DBE
∵∠EDB=100°
∴∠DEB=∠DBE=40°
∵∠AED=140°
∵∠A=∠ADE
∴∠A=20°
∵∠ABC=100°
∴∠A+∠C=80°
∵AE=ED
∴∠A=∠ADE
∵BD=BC
∴∠BDC=∠C
∵∠ADE+∠BDC=80°
∴∠EDB=100°
∵ED=BD
∴∠DEB=∠DBE
∵∠EDB=100°
∴∠DEB=∠DBE=40°
∵∠AED=140°
∵∠A=∠ADE
∴∠A=20°