What function has an inverse that is also a function

Free 100 points to whoever says “oof the porridges” if it’s not exact, your answer will be reported, first person gets brainliest

Scott harris can invest $7,000 in a 1-year cd that earns interest at an annual rate of 4 percent compounded monthly. the amount per $1.00 is 1.040742. he can also invest $7,000 in a 1-year cd at annual rate of 4 percent compounded quarterly. the amount per $1.00 is 1.040604. what is the difference in the amount of interest earned for each investment? a) $0.96 b) $0.81 c) $0.87 d) $0.88

If i have 20$ and i gave 5$ away how much i got