Since the quadrilaterals are similar their corresponding angles must be equal.

Thus angle A = angle H that implies 2x + 4 = 68 OR x = 32 degree

Also angle L = angle D = 3x - 6, Plug in the value of x which we just calculated i.e., x = 32 we get

angle L = 3 * 32 - 6 = 96-6=90 degree