Explanation:
KLH is a triangle, and the sum of all angles in a triangle is 180°.
now, we know the angle at L = 134°.
because of the symmetry of the angles in such a regular parallelogram, the upper angle at H is 25°, and the lower angle at H (one of the angles in our triangle) is (4x + 9)°.
and the upper angle at K is (4x + 9)°, and the lower angle at K is 25°.
so, we have
180 = 134 + 25 + (4x + 9) = 159 + 4x + 9 = 168 + 4x
12 = 4x
x = 12/4 = 3