This question is related to Multi Calculus can u please give me answer as soon as posible with proper steps

The temperature in a certain region of space, in degrees Celsius, is modeled by the function T(x, y, z) = 20e-16-2y"-42", where r, y, z are measured in meters. At the point a = (2, -1,3): (a) In what direction is the temperature increasing most rapidly? (b) In what direction is it decreasing most rapidly? (c) If you travel in the direction described in part (a) at a speed of 10 meters/second, how fast is the observed temperature changing at a in degrees per second