Final answer:
The student's question involves calculating the speed of a boat in still water, addressing the influence of a river's current on the boat's motion. This relates to kinematics, a part of physics.
Step-by-step explanation:
The question pertains to the physics of relative motion in a fluid, where the aim is to determine the speed of the boat in still water. Since the question involves calculations for speed, time, and direction of the motion of a boat in a river and the effects of the river's current on the boat's travel, concepts such as velocity vectors and relative motion are required. This falls under the subject of physics, specifically within the domain of kinematics.