The gravity of earth is the constant 9.8m/s^2. when an object is propelled upwards gravity works as negative acceleration. Air resistance is ignored

a) find v(t), velocity in terms of time, of an object propelled straight up with an initial velocity (at t=0) of 20 m/s

b) Given v(t), find the height function for the object given that the object begins its upward trajectory at a height of 1.5m

c) Find the maximum height reached by the object

i just have noooo idea what to do here!