(Asuming we are asked to calculate the final value of the car with 30% discount)
If we want to calculate the y percentage of x quantity (y% of x) , we just have to do the following:

In this case, the car has a 30% discount. So we ought to calculate the 70% of the original value:

Thus, the final value of the car, after discounting 30% of its original price, would be $37,100