When subtracting 6.4 from a certain number, the result is 55.94, as seen below. What number should go in the box to complete the subtraction problem? The decimal 6.4 is subtracted from an unknown whole number to get 55.94. The unknown whole number has 6 in the tens place, an unknown number in the ones place, 3 in the tenths place, and 4 in the hundredths place.

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! "?