a company maufacturing surfboards has fixed costs of $300 per day and total costs of $5100 per day for a daily output of 20 boards. Assume the total cost per day C(x) is linearly related to the total output per day x. write an equation for the cost function, and write an equation for the average cost function Ċ(x)=c(x)/x. what does the average cost per board tend to as production increases (assume production output goes to infinity)?