Alyssa paid a plumber x dollars per hour for a 6-hour period, plus $70 for parts. the total charge was $172. what is the equation for how much money the plumber is charged per hour ?

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.