∵角A+角C=2角B∴角A+角B+角C=3角B=180°∴角B=60°∵角C-角A=80°∴角C=角A+80°∴角A+角C=角A+角A+80°=2角A+80°=2角B=120°∴角A=20°∴角A补角=180°-20°=160°
