if you integrate velocity, you get distance, this must be well known in any calc class or calc based physics class

since integration is a way to find the area under a curve, you must simply compute the area from 0 to 50

for part b, you have a graph with velocity of the fist and you are looking for the maximum speed of the fist. Speed is the absolute value of velocity, but the velocity is never negative so speed=velocity in this case

can you read the max velocity off of the graph?