Final answer:
To represent Gabriel's weekly paycheck, the linear equation used is P = 4000 + 50C, where 'P' is the total amount paid and 'C' is the number of cars sold.
Step-by-step explanation:
Gabriel's weekly paycheck can be calculated using a linear equation which includes a fixed salary component and a variable commission component based on the number of cars sold. The fixed salary is $4,000, and the commission is $50 for each car sold. To represent Gabriel's weekly paycheck P, where C is the number of cars, the equation is given by P = 4000 + 50C. Therefore, the correct option is D) P = 4000 + 50C. This equation ensures that even if Gabriel does not sell any cars in a week, he still earns his fixed salary of $4,000, and for each car he sells, his earnings increase by $50.