To calculate percentage, multiply the percent (as a decimal) by the price paid. Since we don't know what the dealer paid, we'll use x to represent the price the dealer paid. Therefore, the 12% added on would be .12x.
Since the markup is added to the original price to get the final price, this gives us the equation:
x + .12x = 6999
1.12x = 6999
x = 6249.11 (Option B)