How do you write an equation using an exponent that would express the 100-year total rainfall for New York city?

To express the 100-year total rainfall for New York City using an exponent, you can represent the average annual rainfall as a base and use a power to indicate the number of years. If the average annual rainfall is, for example, ( R ) inches, the equation would be ( T = R \times 100 ), where ( T ) is the total rainfall over 100 years. Alternatively, if you're focusing on a cumulative growth model, you might use ( T = R \times (1 + r)^{100} ), where ( r ) is the growth rate of rainfall, if applicable.