Question

Two angle of a quadrilateral are supplementary . If one of the remaining angle is 65 degree determine the fourth angle .

Answer 1

Let forth angle be x

so by the condition given in your question we get equation

180 + 65 + x = 360

245 + x = 360

x = 360 - 245

x = 115

so forth angle of quadrilateral is 115

Answer 2

let the name of the quadrilateral be quadABCD
and angle A +angle C =180 {they are supplementary} and angle B=65degrees
the sum of the angles of a quadrilateral is 360degrees
so angle A+B+C+D =360
              A+C+B+D=360
             180+65+D=360
              D=360- 245
             D=115
THUS THE MEASURE OF THE FOURTH ANGLE OF THE QUADRILATERAL IS 115DEGREES.