Melissa says the gcf of 8x2y + 4xy is 4. adam says the gcf is 4y. erica says the gcf is 4xy. who is correct? in complete sentences explain your answer, and factor the expression.

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! "?