How the position of the decimal point changes in a quotient as you divide by increasing powers of 10

For how answer my question this will be the last question can you answer in math subject

Which of the following tables represents exponential functions?

You just purchased two coins at a price of $670 each. because one of the coins is more collectible, you believe that its value will increase at a rate of 7.1 percent per year, while you believe the second coin will only increase at 6.5 percent per year. if you are correct, how much more will the first coin be worth in 15 years?