What critical assumptions has TESLA made to value inventory? Does TESLA use FIFO or LIFO? Explain what is LCM (the lower of cost or market) and how this may impact inventory every year.

During the years ended December 31, 2019, 2018 and 2017, we recorded write-downs of $138 million, $78 million and $124 million, respectively, in cost of revenues. Our inventory consisted of the following (in $millions):8 Raw materials Work in process Finished goods Service parts Total December 31, 2019 1,428 362 1,356 406 3,552 December 31, 2018 932 297 1,581 303 3,113