Question 1204771
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DB = DC which makes triangle BDC isosceles.
It will mean base angles B and C are congruent.
In other words, angle DBC = angle DCB.
Let x represent the measure of each base angle.
The congruent base angles are opposite the congruent sides.


Because BC is parallel to DE (due to the arrow markers), we know that alternate interior angles BCD and EDC are congruent. 
Both are x.


Triangle DEC is isosceles since DE = CE. 
The congruent base angles are D and C (aka angle EDC and angle ECD). 
Each of these angles are x.


Focus on triangle DEC. Use the remote interior angle theorem to find that (angleEDC)+(angleECD) = angleAED
Or you can use the corresponding angles theorem to see that angle ACB = angle AED.
This will lead to angle AED = 2x


Use the corresponding angles theorem to note that angle ADE = angle ABC = x.


Here's a diagram summarizing all that we found so far
*[illustration Screenshot_348.png]
From here focus on triangle AED. 
For any triangle, the interior angles <b>always</b> add to 180 degrees.
A+E+D = 180
42+2x+x = 180
I'll let you take over from here.
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