please try show all steps so i can understand. Thanks in advance!

g 2) The position function ofa moving object is 5(t) = \"(7 - t), where 0 5 t S 20. The position sit) is given in metres and time t, in seconds. a. Calculate the object's velocity at any time t. b. When does the object return to its original position? c. When does the motion of the object change direction? d. When does the object move away and when toward the starting point. e. Calculate the object's acceleration at any time t. f. When is the acceleration positive, and when is it negative? 5. Determine the time intervals when the object is speeding up or slowing down