...That's due tomorrow? Isn't that... cutting it a bit close? :/
Either way. C++ has a few functions to deal with some basic mathematics, including one for exponentials. In fact, your teacher gave a hint as to what it is: exp(). Subtle hint, but it was there. ;)
When you write your program, you will probably want to avoid using any integers. Every single number should end with a decimal point, and you'll probably want to define t as a double.
If you want any further help, feel free to ask for more!