Please look at the question and solution below. I have the answer

Please look at the question and solution below. I have the answer but need to know how they did the mathematical step to obtain the solution. I have tried it several ways and it is still wrong. Can you please show me how they are obtaining the solution?,,Suppose a company uses trade credit with the terms of 2/10, net 50. If the company pays,their account on the 50th day, the effective borrowing cost of skipping the discount on,day 10 is closest to:,A. 14.9%.,B. 15.0%.,C. 20.2%.,,Answer is: C ,Cost = (1 + 0.02/0.98) 365/40 – 1 = 20:24%