Table:
|  | Years Ended December 31, |  |
| --- | --- | --- |
|  | 2019 | 2018 |
| Sales | $  — | $  — |
| Cost of sales | (901) | (88) |
| Total operating expense | 1,022 | 96 |
| Operating income (loss) from discontinued operations | (121) | (8) |
| Other income (expense) | 10,895 | (24) |
| Income (loss) from discontinued operations before income taxes | 10,774 | (32) |
| Provision (benefit) for income taxes | 2,294 | 6 |
| Income (loss) from discontinued operations, net of income taxes | $8,480 | $(38) |
Paragraphs:
Discontinued Operations
In December 2015, we completed the wind down of engineering, manufacturing and sales of our solar inverter product line (the "inverter business"). Accordingly, the results of our inverter business have been reflected as “Income (loss) from discontinued operations, net of income taxes” on our Consolidated Statements of Operations for all periods presented herein.
The effect of our sales of extended inverter warranties to our customers continues to be reflected in deferred revenue in our Consolidated Balance Sheets. Deferred revenue for extended inverter warranties and the associated costs of warranty service will be reflected in Sales and Cost of goods sold, respectively, from continuing operations in future periods in our Consolidated Statement of Operations, as the deferred revenue, is earned and the associated services are rendered. Extended warranties related to the inverter product line are no longer offered.
ADVANCED ENERGY INDUSTRIES, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS – (continued) (in thousands, except per share amounts)
The significant items included in "Income (loss) from discontinued operations, net of income taxes" are as follows:
Question:
What was the percentage change in Cost of sales between 2018 and 2019?
Answer: (-901-(-88))/-88 = 923.86