The solution to the problem is as follows:
Average cost is c(x)/x.
c(35) = 400 + 20(35) - 0.2(35)^2 = $855.
Then, the average cost is $855/35 = $24.43/radio
I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!