b) The vertical height (in feet) of an elevator moving upward as a function of time (in seconds) is represented by the equation

h = 5t + 1

How fast does the vertical height change, in feet per second?

c) The speed of an ostrich, s, in meters per second, for its first seven seconds of travel is described by the equation

s = 3t

where t is the time of travel. How fast is the ostrich moving after three seconds?