$5850
If 100% of the car price is 24,600 , then you need to find what 15% is.
To do this you can use the percentage formula:
Amount x [tex]\frac{percentage}{100}[/tex]
Now, you can simply plug the values into this
39000 x [tex]\frac{15}{100}[/tex]
39000 x 0.15 = 5850
