1. 1. If you deposit $15000 in an account that pays 5% interest, how much will you have after at the end of 5 years? 10 years? And 20 years?
2. 2. Edward needs $500 now for a project and will pay you back $570 in a year. Is that a good investment when you can get 10% elsewhere? 
3. hint: if accept it, you must reject it for less than 0)