1. Mr Williams deposited 50,000 USD 5 years ago in a bank account that pays a 3% interest rate per year. 3 years ago, Mr. Williams withdrew 10,000 USD from his account, and he did the same one year ago. How much money Mr. Williams has in the bank account today?

2. Mr. Short did a deposit of 100,000 USD in his bank account 10 years ago. Ever since then, Mr. Short has deposited 5,000 USD 5 years ago, 6.000 USD 4 years ago and 7.000 USD 3 years ago. What is the current balance of his account assuming the bank has been paying 2% of interest every year?

3. Now suppose that Mr. Short has managed to negotiate an increase in the annual interest rate from 2% to 2.5%, starting in the beginning of the third year and from 2.5% to 3% starting in the beginning of the sixth year. Under these new conditions, what would be the account balance today?