Need help!! “Use the Pythagorean theorem to find the missing side of the right triangle.”

Will mark ! (10 points also! ) if x varies inversely with y and x =6 when equals y= 10, find y when x=8 a. y=4.8 b. y=7.5 c. y=40/3 d. y=4/15

Me i'm timed ! a. -2 to 1 b. -1.5 to 0.5c. 0 to 1d. 0.5 to 1.5

Use stokes' theorem to evaluate c f · dr where c is oriented counterclockwise as viewed from above. f(x, y, z) = xyi + 5zj + 7yk, c is the curve of intersection of the plane x + z = 8 and the cylinder x2 + y2 = 81.