Please help with this question thank you

The temperature at a point (x, y, 2) is given by T(x, y, z) = 400e-*2 - 5y2 - 722 where 7 is measured in C and x, y, z in meters. (a) Find the rate of change of temperature at the point P(4, -1, 4) in the direction towards the point (5, -4, 5). oc/m X (b) In which direction does the temperature increase fastest at P? X (c) Find the maximum rate of increase at P. X