Answer: 510°
Explanation:
1st. solution.
Draw the perpendicular EP ⊥FB.
So from quadrilateral FAEP we find the∡AEP ( sum of all angles in quadrilateral=360°)
∡AEP= 360°-∡FAE-∡AFP-∡FPE=360°-20°-90°-90°=160°
Draw CK ⊥FB
From triangle CKB we can find ∡BCK=180°-10°-90°=80°
From pentagon PEDCK (sum of PEDCK angles= 540°) we can find the sum of ∡PED+∡DCK= 540°-∡EPK-∡EDC-∡CKP= 540°-90°-90°-90°=270°
∡DEA+∡DCB=∡AEP+∡PED+∡DCK+∡KCB=160°+270°+80°=510°