Table:
| Years Ended | July 27, 2019 | July 28, 2018 | July 29, 2017 |
| --- | --- | --- | --- |
| Amortization of purchased intangible assets: |  |  |  |
| Cost of sales | $624 | $640 | $556 |
| Operating expenses |  |  |  |
| Amortization of purchased intangible assets | 150 | 221 | 259 |
| Restructuring and other charges | — | — | 38 |
| Total | $774 | $861 | $853 |
Paragraphs:
Amortization of Purchased Intangible Assets
The following table presents the amortization of purchased intangible assets (in millions):
The decrease in amortization of purchased intangible assets was due largely to the purchased intangible assets related to the divestiture of SPVSS business on October 28, 2018, partially offset by amortization from our recent acquisitions.
Question:
Why did amortization of purchased intangible assets decrease?