($ in millions)
For the year ended December 31:
2019
2018
Yr.-to-Yr. Percent Change
External revenue
$1,400
$1,590
(11.9) %
Internal revenue
1,232
1,610
(23.5)
Total revenue
$2,632
$3,200
(17.8) %
Pre-tax income
$1,055
$1,361
(22.5) %

text: In 2019, Global Financing delivered external revenue of $1,400 million and total revenue of $2,632 million, with a decrease in gross margin of 2.7 points to 58.8 percent. Total pre-tax income of $1,055 million decreased 22.5 percent compared to 2018 and return on equity decreased 5.0 points to 25.8 percent.
text: Global Financing total revenue decreased 17.8 percent compared to the prior year. This was due to a decrease in internal revenue of 23.5 percent, driven by decreases in internal used equipment sales (down 27.4 percent to $862 million) and internal financing (down 12.6 percent to $370 million). External revenue declined 11.9 percent due to decreases in external financing (down 8.5 percent to $1,120 million) and external used equipment sales (down 23.4 percent to $281 million).
text: The decrease in internal financing revenue was due to lower average asset balances, partially offset by higher asset yields. The decrease in external financing revenue reflects the wind down of the OEM IT commercial financing operations.
text: Sales of used equipment represented 43.4 percent and 48.5 percent of Global Financing’s revenue for the years ended December 31, 2019 and 2018, respectively. The decrease in 2019 was due to a lower volume of internal used equipment sales. The gross profit margin on used sales was 52.2 percent and 54.2 percent for the years ended December 31, 2019 and 2018, respectively. The decrease in the gross profit margin was driven by lower margins on internal used equipment sales.
text: Global Financing pre-tax income decreased 22.5 percent year to year primarily driven by a decrease in gross profit ($422 million), partially offset by a decrease in total expense ($115 million), which was mainly driven by a decline in IBM shared expenses in line with the segment’s performance, a lower provision for credit losses and a gain from the sale of certain commercial financing capabilities in the first quarter of 2019.
text: The decrease in return on equity from 2018 to 2019 was primarily due to lower net income. Refer to page 45 for the details of the after-tax income and return on equity calculations.

Questions:
question: What caused the Global Financing total revenue to decrease?
answer: This was due to a decrease in internal revenue of 23.5 percent, driven by decreases in internal used equipment sales (down 27.4 percent to $862 million) and internal financing (down 12.6 percent to $370 million).
question: What caused the internal financing revenue to decrease?
answer: The decrease in internal financing revenue was due to lower average asset balances, partially offset by higher asset yields. The decrease in external financing revenue reflects the wind down of the OEM IT commercial financing operations.
question: What caused the sales of used equipment to decrease?
answer: The decrease in 2019 was due to a lower volume of internal used equipment sales.
question: What is the average External revenue?
answer: 1495
derivation: (1,400 + 1,590) / 2
scale: million
question: What is the increase / (decrease) in the internal revenue from 2018 to 2019?
answer: -378
derivation: 1,232 - 1,610
scale: million
question: What percentage of total revenue is Pre-tax income in 2019?
answer: 40.08
derivation: 1,055 / 2,632
scale: percent