instruction:
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.
question:
Passage: The Lines of Communication were English Civil War fortifications commissioned by Parliament  and built around London between 1642 and 1643 to protect the capital from attack by the Royalist armies of Charles I. In 1642 some basic fortifications were built, in the form of street barricades and small earthworks. In 1643 a major construction effort was made, to provide a comprehensive ring of fortifications around the city. Much of the work was done by volunteer labour, organized by the trained bands and the livery companies. Up to 20,000 people are thought to be involved, and the works were completed in under two months. The fortifications failed their only test when the New Model Army entered London in 1647, and they were levelled by Parliament the same year.
answer:
How many months did it take them to build The Lines of Communication?


question:
Passage: The population of the city proper is 370,702, while Eurostat estimates that 696,767 people live in the Larger Urban Zones of Florence. The Metropolitan Area of Florence, Prato and Pistoia, constituted in 2000 over an area of roughly , is home to 1.5 million people. Within Florence proper, 46.8% of the population was male in 2007 and 53.2% were female. Minors (children aged 18 and less) totalled 14.10 percent of the population compared to pensioners, who numbered 25.95 percent. This compares with the Italian average of 18.06 percent (minors) and 19.94 percent (pensioners). The average age of Florence resident is 49 compared to the Italian average of 42. In the five years between 2002 and 2007, the population of Florence grew by 3.22 percent, while Italy as a whole grew by 3.56 percent. The birth rate of Florence is 7.66 births per 1,000 inhabitants compared to the Italian average of 9.45 births.
answer:
By how many points lower is Florence's brith rate than that of the Italian average?


question:
Passage: An important element the Revolution's legacy is the 1917 Constitution. It was pushed forward by populist generals within Carranza's government to undermine the popular support that Pancho Villa and Emiliano Zapata held. It was not written by liberal elites or the military itself, but rather young radicalized professionals, giving the document some authenticity for the peasantry. The document brought numerous reforms demanded by populist factions of the revolution, with article 27 empowering the state to expropriate resources deemed vital to the nation. These included expropriation of hacienda lands and redistribution to peasants. Article 27 also empowered the government to expropriate holdings of foreign companies, most prominently seen in the 1938 expropriation of oil. In Article 123 the constitution codified major labor reforms, including an 8-hour work day, a right to strike, equal pay laws for women, and an end to exploitative practices such as child labor and company stores. The constitution strengthened restrictions on the Roman Catholic Church in Mexico. In the early 1990s, the government introduced reforms to the constitution that rolled back the government's power to expropriate property and its restrictions on religious institutions. Just as the government of Carlos Salinas de Gortari was amending significant provisions of the constitution, Metro Constitución de 1917 station was opened.
answer:

How many full decades were there between the passage of the 1917 Constitution and the enactment of of reforms that rolled back the government's power to expropriate property?