Professor J can grade an entire section of essays in 3 hours. His teaching assistant, M, can grade the same amount of essays in 5 hours. How long would it take them to grade the essays if they work together?
(15points) plz help!

Abank manager wants to encourage new customers to open accounts with principals of at least $2 comma 500. he decides to make a poster advertising a simple interest rate of 3%. what must the principal be if the bank manager also wants to advertise that one can earn $10 the first month? can the poster correctly say, "open an account of $2 comma 500 and earn at least $10 interest in 1 month! "?