PLEASE HELP ASAP Is the function ƒ(x) = (9/10)^x an exponential function? If so, identify the base. If not, why not?

After two years, how much has been paid into interest?

Can someone answer this question? : )

Aaron invested a total of $4,100, some in an account earning 8% simple interest, and the rest in an account earning 5% simple interest. how much did he invest in each account if after one year he earned $211 in interest? select one: a. $200 at 8%, $3,900 at 5% b. $3,200 at 8%, $900 at 5% c. $900 at 8%, $3,200 at 5% d. $3,900 at 8%, $200 at 5%