Hello again! This is my answer to the problem:

We know that the sum of interior angles in a triangle is 180 degrees. So the triangle made up of C, E, and the final, unlabled point (I am going to call this Y), must have this sum. This means that BCD must be less than 180-120=60 degrees.

I can find angle CDA, 180 (the number of degrees in a line) - 60 (the number of degrees we already know are on the line), which gives us 120.

Using this data, 180-(120+21 [the sum of the angles we alread know in the DYA triangle])=39 degrees, the number of degrees that are in angle AYD.

Because the angles are symmetric, angle CYE is also 39 degrees.

To finish this problem off, BCD is the same as ECD. When we know that two angles are 39 and 120, the final answer is that ECD/BCD is 180-(39+120) = 21 degrees.

To check, 21<60, so our answer does work!

**BCD is 21 degrees.**

Thank you so much for making an image, this really helped me solve the problem! I hope this helped!

The Math Whiz