In $$\triangle ABC, AB = 20$$ cm, BC = 21 cm and AC = 29 cm. What is the value of $$\cot C + \cosec C - 2 \tan A$$?

A

$$\frac{3}{5}$$

B

$$\frac{9}{20}$$

C

$$\frac{2}{5}$$

D

$$\frac{7}{20}$$