Solution: 19.7 * (1+x) 2 = 25.
2. Deposit 10000 yuan in the bank, with the annual interest rate of X%, and deposit the principal and interest for another year after the expiration of one year, with the annual interest rate unchanged. At maturity, the sum of the principal and interest is _ _ _ _ ten thousand yuan.
Solution: 1 * (1+x%) 2