<PRE><B>Question 422184</B>
Two opposite angles of a parallelogram

two adjacent angles are supplementary.
If you draw a parallelogram                  A --------------B
                                             -            -
                                            -            -
                                           D------------C
let us say angle dab is 3x+40         angle DCB = x+50

angle ADC =180-(3x+40)
two adjacent angles are supplementary

so 180-(3x+40)+x+50=180

180 cancels.
-3x-40+x+50=0
-2x+10=0
2x=10
x=5
angles are 3x+40=3*5+40=55
x+50=55  </PRE>