![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
Opposite sides of a parallelogram are congruent.Opposite sides of a parallelogram are congruent.
So, ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=bcb5f538a89990ce2b0d73767dc67c28.png\")
.
(Definition of congruent angles)
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=a4d56eacbcc45374cee291c7de5e933b.png\")
(Substitute ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=ce3ff3e32ae0fa877901f22789aba8f2.png\")
)
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=886bc41ae64aff00881f469c479bf7fa.png\")
(Divide each side by 3)![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
The value of a is 7.