We can help; but of course, since the goal is to help you learn the topic, we'll have to know what parts of the topic you need help with, so you can then do the assignment on your own (to show that you did learn it).
So please either show an attempt at the work so we can guide you through what you can't do, or ask some specific questions that we can answer (or maybe provide a link to learning materials on the topic).
When you show work, it will be helpful if you show exponents properly, which could either be "M = 2e-3t" using the "superscript" button on the edit bar, or "M = 2e^(-3t)" using standard typed notation, or "[MATH]M = 2e^{-3t}[/MATH]" using the "calculator" button that takes LaTeX codes, or in handwriting in an attached image.