3. Depreciation expenses and impairment losses
| (in millions of euros) | Note | 2021 | 2020 | 
| Cost of depreciation of Property, plant and equipment | 11 | 261 | 335 | 
| Cost of depreciation of Investment property | 12 | 7 | 8 | 
| Cost of amortisation of Intangible assets | 13 | 74 | 84 | 
| Cost of depreciation of Right-of-use assets | 30 | 476 | 482 | 
| Total cost of depreciation and amortisation | 818 | 909 | |
| Impairments of Property, plant and equipment | 11 | 2 | 1,474 | 
| Impairments of Intangible assets | 13 | 1 | 148 | 
| Impairments of Right-of-use assets | 30 | 13 | 111 | 
| Total impairments | 16 | 1,733 | |
| Reversal of impairments of Property, plant and equipment | 11 | (98) | (2) | 
| Reversal of the impairments of Intangible assets | 13 | (3) | - | 
| Reversal of impairments of Right-of-use assets | 30 | - | (3) | 
| Total reversal of impairments | (101) | (5) | |
| Total | 733 | 2,637 | |
For the explanation of impairments of non-current assets, reference is made to note 14.