Answer:
Think simple.
We already have parallelogram LENS, therefore:
∠L ≅ ∠ENS
We also have parallelogram NGTH, therefore:
∠T ≅ ∠GNH
Finally, we can also see that:
∠ENS ≅ ∠GNH (opposite angles)
=> ∠L ≅ ∠T