The slope of the line passing through the points
and
can be calculated using the formula

Since the graph of the line passes through the points (4,41) and (7,71.75), the slope of this line is

In this situation this means that Dante earns $10.25 per hour, because you have divided the amount of money that Dante earned during 3 hours by 3 that is the number of hours Dante worked to earn $30.75.
Answer: correct choice is B