physics worksheet

i neeed help with physics question. it is a worksheet with around 15 questions. not wiling to pay over 15$ here is a sample question: A world-class sprinter accelerates to his maximum speed in 3.8 s. He then maintains this speed for the remainder of a 100-{\rm m} race, finishing with a total time of 9.3 s. Part A What is the runner's average acceleration during the first 3.8 s? Express your answer using two significant figures. Part B What is his average acceleration during the last 5.5 s? Express your answer using two significant figures. Part C What is his average acceleration for the entire race? Express your answer using two significant figures.