The temperature at a point (x, y) is T(x, y), measured in degrees Celsius. A bug crawls so that its position after t seconds is given by x = squareroot l + t, y = 4 + 1/8t, where x and y are measured in centimeters. The temperature function satisfies T_x(3, 5) = 7 and T_y(3, 5) = 2. How fast is the temperature rising on the bug's path after 8 seconds? () ________ degree C/s