The Hotak dynasty  was an Afghan monarchy of the Ghilji Pashtuns, established in April 1709 by Mirwais Hotak after leading a successful revolution against their declining Persian Safavid overlords in the region of Loy Kandahar  in what is now southern Afghanistan. It lasted until 1738 when the founder of the Afsharid dynasty, Nader Shah Afshar, defeated Hussain Hotak during the long siege of Kandahar, and started the reestablishment of Iranian suzerainty over all regions lost decades before against the Iranian archrival, the Ottoman Empire, and the Russian Empire. At its peak, the Hotak dynasty ruled briefly over an area which is now Afghanistan, Iran, western Pakistan, and some parts of Tajikistan and Turkmenistan. In 1715, Mirwais died of a natural cause and his brother Abdul Aziz succeeded the monarchy. He was quickly followed by Mahmud who ruled the empire at its largest extent for a mere three years. Following the 1729 Battle of Damghan, where Ashraf Hotak was roundly defeated by Nader Shah, Ashraf was banished to what is now southern Afghanistan with Hotak rule being confined to it. Hussain Hotak became the last ruler until he was also defeated in 1738.
Question: How many years after the Hotak dynasty was founded did the Battle of Damghan take place?
Answer: 20