Final answer:
The correct equation for the total cost of the plumber's service for h hours is C = 25 + 39.50h, including a $25 service fee and $39.50 per hour of work.
Therefore, the correct answer is: option D). C = 25 + 39.50h
Step-by-step explanation:
The plumber charges a $25 service fee plus $39.50 per hour of work.
To represent the total cost, C, for the plumber's service when he works h hours, we need to use a linear equation that includes both the fixed fee and the variable hourly charge.
The correct equation to represent the total cost is: C = 25 + 39.50h
This equation has two components: the fixed service fee of $25, which is the y-intercept, and the hourly rate of $39.50, which is the slope of the equation.
This means for every additional hour the plumber works, the total cost increases by $39.50.