Detailed Instructions: This task involves creating answers to complex questions, from a given passage. Answering these questions, typically involve understanding multiple sentences. Make sure that your answer has the same type as the "answer type" mentioned in input. The provided "answer type" can be of any of the following types: "span", "date", "number". A "span" answer is a continuous phrase taken directly from the passage or question. You can directly copy-paste the text from the passage or the question for span type answers. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words. A "number" type answer can include a digit specifying an actual value. For "date" type answers, use DD MM YYYY format e.g. 11 Jan 1992. If full date is not available in the passage you can write partial date such as 1992 or Jan 1992. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words.
See one example below:
Problem: Passage: The outbreak of the Seven Years' War in Europe in 1756 resulted in renewed conflict between French and British forces in India. The Third Carnatic War spread beyond southern India and into Bengal where British forces captured the French settlement of Chandernagore in 1757. However, the war was decided in the south, where the British successfully defended Madras, and Sir Eyre Coote decisively defeated the French, commanded by Comte de Lally at the Battle of Wandiwash in 1760. After Wandiwash, the French capital of Pondicherry fell to the British in 1761. The war concluded with the signing of the Treaty of Paris in 1763, which returned Chandernagore and Pondichery to France, and allowed the French to have "factories" in India but forbade French traders from administering them. The French agreed to support British client governments, thus ending French ambitions of an Indian empire and making the British the dominant foreign power in India.
Question: Which french settlement did the British capture first, Chandernagore or Pondicherry
Answer type: Span
Solution: Chandernagore
Explanation: British captured Chandernagore in 1757 ("The Third Carnatic War spread beyond southern India and into Bengal where British forces captured the French settlement of Chandernagore in 1757") and Pondicherry in 1761 ("After Wandiwash, the French capital of Pondicherry fell to the British in 1761."). Since 1757<1761, the answer is "Chandernagore".

Problem: Passage: Although nominally part of the Ottoman Empire, Yemen and the sahil came progressively under the control of Muhammad Ali, ruler of Egypt, between 1821 and 1841. After the Egyptians withdrew from the Yemeni seaboard in 1841, Haj Ali Shermerki, a successful and ambitious Somali merchant, purchased from them executive rights over Zeila. Shermerki's governorship had an instant effect on the city, as he manoeuvred to monopolize as much of the regional trade as possible, with his sights set as far as Harar and the Ogaden. Shermerki was later succeeded as Governor of Zeila by Abu Bakr Pasha, a local Afar statesman. In 1874-75, the Egyptians obtained a firman from the Ottomans by which they secured claims over the city. At the same time, the Egyptians received British recognition of their nominal jurisdiction as far east as Cape Guardafui. In actuality, however, Egypt had little authority over the interior and their period of rule on the coast was brief, lasting only a few years . The British Somaliland protectorate was subsequently established in the late 1880s, after the ruling Somali authorities signed a series of protection treaties granting the British access to their territories on the northwestern coast. Among the Somali signatories were the Gadabuursi , Habar Awal , and Warsangali. When the Egyptian garrison in Harar was eventually evacuated in 1885, Zeila became caught up in the competition between the Tadjoura-based French and the British for control of the strategic Gulf of Aden littoral. By the end of 1885, the two powers were on the brink of armed confrontation, but opted instead to turn negotiations. They later signed a convention on 1 February 1888 defining the border between French Somaliland and British Somaliland.
Question: How many years did Muhammad Ali rule Yemen and the sahil?
Answer type: Number
Solution:
20.