Answer:
C. 1000 loss.
Step-by-step explanation:
Let x represent purchase price of each car.
We have been given that a used-car dealer sold one car at a profit of 25 percent of the dealer's purchase price for that car and sold another car at a loss of 20 percent of the dealer's purchase price for that car.
We can represent the car that dealer sold with 25% profit to find purchase price as:




Therefore, the purchase price of 1st car was $16,000.
We can represent the car that dealer sold with 20% loss to find purchase price as:




Therefore, the purchase price of 2nd car was $25,000.
The total purchase price of both cars would be 
The total sale price of both cars
.
We can see that the sale price of both car is less than purchase price by $1000, so the dealer got a loss of $1000.
Therefore, the dealer's total loss, in dollars, for the two transactions combined was 1000 and option C is the correct choice.