Table:
|  | As at December 31 | As at December 31 |
| --- | --- | --- |
| (In millions of dollars) | 2019 | 2018 |
| Wireless devices and accessories | 380 | 399 |
| Other finished goods and merchandise | 80 | 67 |
| Total inventories | 460 | 466 |
Paragraphs:
ACCOUNTING POLICY
We measure inventories, including wireless devices and merchandise for resale, at the lower of cost (determined on a weighted average cost basis for Wireless devices and accessories and a first-in, first-out basis for other finished goods and merchandise) and net realizable value. We reverse a previous writedown to net realizable value, not to exceed the original recognized cost, if the inventories later increase in value.
EXPLANATORY INFORMATION
Cost of equipment sales and merchandise for resale includes $2,496 million of inventory costs for 2019 (2018 – $2,515 million).
Question:
How is lower of cost determined?