Angle one equals 125 angle two equals 55 angle three is greater than angle four by 20 which equals angle four.

Obviously, the problem is about a quadrilateral. The sum of the angles of a quadrilateral is 360 °
We introduce the variable x and denote this by the degree measure of the fourth angle, then the degree measure of the third angle is (x + 20). The sum of all angles is known, we get the equation:
125 ° + 55 ° + x + 20 ° + x = 360 °
2x = 160 °
x = 80 ° – the fourth angle.
Answer: the degree measure of the fourth angle is 80 °.