Reviewing for my board exam ... Got no idea in solving this problem.

Find the length of subtangent, subnormal, tangent and normal of $\displaystyle xy + 2x - y = 5$ at point (2,1)

a. 1, 1 / 3, sqrt of 10 / 2, sqrt of 10

b. 1, 3, 5, 7

c. 1, 3, sqrt of 10 / 3, sqrt of 10

d. -1 / 3, -3, sqrt of 10 / 3, sqrt of 10