Given the task definition and input, reply with output. This task involves creating questions from a given passage that involve some kind of complex reasoning (including numerical reasoning).
The generated questions must require looking at more than one part of the passage to answer. Try to use a variety of reasoning types in your questions (some of the sample reasoning types are illustrated in the 'positive examples' field) and also have a variety of answer types (spans, numbers, dates). A span is a continuous phrase taken directly from the passage or question. In such questions, the answer spans are recommended to be five words. Questions with answer type "number", are expected to start with "How many". For instance, "How long did an event last?" can be phrased as "How many years did an event last?". To increase diversity, try to create more questions for which the answer will be multiple spans. Please create questions that require AT LEAST 2 arithmetic operations as illustrated in the 'positive examples' field. You are encouraged to try DIFFERENT COMBINATIONS of operations and not just limit to the combinations shown in those examples. The more challenging questions you create, the better it is.

Passage: The Conference of Ambassadors drew the first demarcation line on June 18. The line, drawn about 5km west of the Warsaw - Saint Petersburg Railway, was based on the military situation on the ground rather than ethnic composition. Neither Poles nor Lithuanians were content with the line. The Polish Ministry of Foreign Affairs rejected the line as it would require the Polish forces to retreat up to 35km . The Lithuanians protested leaving Vilnius and Hrodna under Polish control. As German volunteers were departing from Lithuania and Lithuanian forces were preoccupied with battles against the Soviets in northern Lithuania, Poland mounted an offensive on 100km wide front moving 20-30km deeper into the Lithuanian territory. On July 18, Ferdinand Foch proposed the second demarcation line, known as the Foch Line. It was approved by the Entente on July 26. The Lithuanians were informed about the new line only on August 3. Two major modifications favorable to the Poles were made: the Suwaki Region was assigned to Poland and the entire line was moved about 7km west. Again, both Poles and Lithuanians protested the line as it would require them to withdraw their armies from the Vilnius and Suwaki Regions respectively. German administration, which had not yet retreated from the Suwaki Region, also opposed the Foch Line. The new line did not immediately halt the hostilities. After a couple of Polish attacks on July 29 and August 2, the front stabilized.
Approximately how many km west of the Warsaw-Saint Petersburg Railway did the second line end up being?