The list price is $74.13. Trade discount of 7/21. Find net cost

Step-by-step explanation:

You need to analize the information given in the exercise.

In this case you know that the List price is:

And, based on the data given, you also know that the Trade discount is:

Then, the first step you need to apply is to multiply the List price by the Trade discount, as you can observe below:

 Now it is important to remember that, by definition, the Net cost can be found by subtracting the List price  (which in this case is $74.13) and the product of the List price and the Trade discount (which in this case is $24.71).

Then, through this procedure, you get the following Net cost:

1.

or if you mean (3x^3+5x^2+3x-7)+(8x-6x^2+6):

2.