Angular Velocity and other problems

1) A rotating body has an angular displacement of (teta) radians in time (t) seconds, the relationship between displacement and the time is

(teta) = 7t^3-5t^2+30

find:

angulaer velocity when t = 3second

the acceleration when t = 3

the time when the acceleration = 0

2)

water drain from a cylindrical tank of radius 4 meter. as the height h falls the pressure reduces and it is observer that the relationship h and time t is given by

h= 5e^t/21

find the rate that the heiht is falling after 3 s

the flow rate in liter persecond after 3 seconds

please can someone help me in solving the above problems and an explaination on the method .

thank you in advance.