The interior angles of a pentagon are equal to 540 degrees.
We know 3 out of the 5 angles.
One angle is a box, and the other is x.
Because the one angle is a box, we know it is a right angle, or 90 degrees.
Now, we can add all of these angles together and subtract from 540 to find the missing angle.
90 + 107 + 144 + 138 = 479
540 - 479 = 61
The missing angle is 61.
