Question 812807
In parallelolells (parallelograms) opposite angles are equal, and adjacent angles are supplementary (add to 180).<P>
J and H are opposite angels, so they are equal.  3x-8 = x+20<P>
2x = 28<P>
x = 14<P>
J = 3(14)-8 = 34 = 14+20 = H<P>
O and N are equal.  O+J = 180.  <P>
O + 34 = 180<P>
O = 146 = N<P>
Just to check, the interior angles of a polygon add to 360 degrees.  34+34+146+146 = 360