Table:
| ($ in millions) |  |  |  |
| --- | --- | --- | --- |
| For the year ended December 31: | 2018 | 2017 | Yr.-to-Yr. Percent Change |
| Results of Operations |  |  |  |
| External revenue | $1,590 | $1,696 | (6.3)% |
| Internal revenue | 1,610 | 1,471 | 9.5 |
| Total revenue | $3,200 | $3,168 | 1.0% |
| Pre-tax income | $1,361 | $1,278 | 6.5% |
Paragraphs:
The increase in Global Financing total revenue was driven by an increase in internal revenue, partially offset by a decrease in external revenue. Internal revenue grew 9.5 percent driven by increases in internal financing (up 17.6 percent) and internal used equipment sales (up 6.8 percent).
External revenue declined 6.3 percent due to a decrease in external used equipment sales (down 30.8 percent), partially offset by an increase in external financing (up 4.9 percent).
The increase in Global Financing pre-tax income was primarily driven by an increase in gross profit and a decrease in total expense.
Question:
What led to decline in External revenue 
Answer: a decrease in external used equipment sales (down 30.8 percent), partially offset by an increase in external financing (up 4.9 percent).