I borrowed 7000 yuan from rural credit cooperatives 20 years ago, and now I have to pay back the principal and interest. The specific rural credit cooperative is Huiyang District, Huizhou City, Guangdong Province. It's about twice the principal. In 10, we doubled it here, which is 7000 yuan. The interest of 10 year is about 7000 yuan (including overdue interest), and overdue interest = normal interest * 1.5 times. The interest for 20 years is about 15000 yuan.