∵∠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°