Step-by-step explanation:
Standard polynomial is:

Leading co effecient is:
-20
Let the length of side AB be $x$, then

Therefore, the perimeter of ABCDE is 2(12) + 2(4) + 6 = 24 + 8 + 6 = 38 in.
So let's say that the second angle is x.
Then we can say that the third angle is
.
So then we have three angles:
1) 66°
2) x°
3) (
)°
So then we can add these together and solve for x by setting it equal to the total degrees left in the triangle after subtracting the known angle:





So now we know that the measure of the second angle is 38°. So then we can use this value to solve for the third angle:

So the values of the angles are:
1) 66°
2) 38°
3) 76°