In ΔABC,
ADDB=43 and AEEC=4.83.6=43
∴ADDB=AEEC=43
We know that in a triangle, if a line segment intersects two sides and divides them in the same ratio, then it will be parallel to the third side.
∴ DE || BC
So, ∠AED=∠ACB=40∘
(Corresponding angles are equal)