Can you solve this triangle puzzle where the answer is not what it seems viral geometry problem

I found this geometry problem on Twitter and nobody in my class can solve it:

In triangle $ABC$, angle $A = 50^\circ$, angle $B = 60^\circ$, angle $C = 70^\circ$.

Point $D$ lies on $AB$ such that $\angle DCB = 30^\circ$.
Point $E$ lies on $AC$ such that $\angle EBC = 20^\circ$.

Find $\angle DEB$.

I tried using the sum of angles in triangles and got multiple possible answers. One person said $30^\circ$, another said $40^\circ$.

I think this requires constructing an equilateral triangle somewhere or using the law of sines. Can someone solve this with a clear geometric construction approach?

Also the answer is apparently $30^\circ$ but I dont see how.