Final answer:
In a word problem, 'miles per hour' best represents the slope of a straight line, which signifies a rate of change, such as speed in driving, cost per hour in services, or the rate of change in stock value.
Step-by-step explanation:
The term that can represent the slope in a word problem is "miles per hour." The slope of a straight line is often related to rates of change in various contexts. For instance, in the context of driving, the rate of change of distance with respect to time is measured in miles per hour, which is indeed the slope of the distance-time graph.
When referring to financial contexts, the slope may represent the rate of change in cost, such as in the case of a cleaning company that charges a certain amount per hour of cleaning. Similarly, in stock market analysis, the slope might indicate the rate at which a stock is gaining or losing value over time, as seen with a stock that has a slope of "-1.5" indicating a loss of $1.50 per hour.