Answer: It would be B 9/50
Step-by-step explanation: if you take 3/7 and x it by 0.1 you get 0.04285714285 and then if you divide that by 5/21 you get 0.18 which equals 9/50 as a fraction
Not much can be done without knowing what

is, but at the least we can set up the integral.
First parameterize the pieces of the contour:


where

and

. You have


and so the work is given by the integral


B. 5 cm, 6 cm, 7 cm . because the sum of two sides should be greater then the 3rd side