∠BDC = ∠A + ∠ABD
∴∠ABD = 20°
∵BD是三角形ABC的角平分线,DE平行CB
∴∠ABD - ∠DBC = ∠EDB = 20°
∴∠C = 180° - ∠EDC = 180° - 20°-70°=90°