In parallelogram J K L M, diagonals J L and K M intersect at point R, and ML is 45, KL is 21. Find m \angle K J L if J K = 2 b + 3 and J M = 3 a.
Choices:
A:30
B:70
C:80
D:100
Please directly answer the question and provide the correct option letter, e.g., A, B, C, D.
Question: In parallelogram J K L M, diagonals J L and K M intersect at point R, and ML is 45, KL is 21. Find m \angle K J L if J K = 2 b + 3 and J M = 3 a.
Choices:
A:30
B:70
C:80
D:100
Please first conduct reasoning, and then answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
Question: In parallelogram J K L M, diagonals J L and K M intersect at point R, and ML is 45, KL is 21. Find m \angle K J L if J K = 2 b + 3 and J M = 3 a.
Choices:
A:30
B:70
C:80
D:100