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put this solution on YOUR website!Recall (or look up) that a sum of all the angles of a quadrilateral is ALWAYS 360 degrees.
So algebraically, this means that:

Start with the given equation.

Remove the parenthesis.

Combine like terms on the left side.

Divide both sides by

to isolate

.

Reduce.
Since

, we can find the angles to be:
Angle #1:
Angle #2:
Angle #3:
Angle #4:
So we have the angles 77, 82, 62, and 139.
We can clearly see that the fourth angle of 139 degrees is the largest.