Final answer:
The equation that represents the cost of a plumber's service is y = 30 + 30x, where x is the number of hours worked and y is the total service cost, including a fixed service call fee and an hourly rate.
Step-by-step explanation:
The equation that represents the cost of a plumber's service which includes a service call fee plus an hourly charge can be written in the slope-intercept form. In this scenario, let x be the number of hours the plumber works and let y be the total cost of the service. The service call fee is a fixed cost, which in terms of the equation, is the y-intercept, and it is equal to $30.00. The additional charge per hour is the variable cost and represents the slope of the equation, which is $30.00 per hour.
The complete equation in slope-intercept form is y = 30 + 30x. This equation indicates that the total cost y is composed of the fixed service call fee ($30.00 when x = 0) plus the hourly charge ($30.00 times the number of hours worked).