this is grade 12 advanced functions and the unit is polynomial functions

On Earth, the height, h, in metres, of a free falling object after t seconds can be modeled by the function h(t) = -4.9t' + k, while on Venus, the height can be modeled by h(t) = -4.45 t' + k, where t 2 0 and k is the height, in metres, from which the object is dropped. Suppose a rock is dropped from a height of 60 m on each planet. For each planet, [4A] (a) Determine the average rate of change of the height of the rock after the first 3 seconds after it is dropped (i.e. Ost $ 3)