I've been stuck on this problem for a long time now. Any help would be super appreciated!

What is the measure of $\angle D$?

Express your answer in degrees rounded to the nearest whole degree.

Let angle D be x. If 2 sides of a triangle are congruent, then 2 of the angles are also congruent. Therefore, we can label the triangle like this:

For the rightmost triangle, we can set up an equation:

\(5x+5x+90-4x=180\)

Can you take it from there?

Thank you so much! I got it!

Use the WHOLE triangle in the diagram

x + 5x + 90 = 180 solve for x