Multiplicative Exponential Demand Function

A regression model is being used to estimate demand for a type of candy. The following multiplicative exponential demand function is being used;

Qd = 6280P^-2.15 A^1.05 N^3.70

^ = raising to a power
Qd = Qty demanded of candy
P = price of candy per piece
A = Advertising expenditure
N = Population of children under the age of 10

a. Determine the advertising elasticity of demand.
b. Determine the point price elasticity of demand.
c. What interpretation would you give to the exponent N?

Here is my question: I understand how to calculate the elasticity of demand however I do not understand how to do this with "powers" and without the ability of having some of the respective costs (example P = 5, A = 1000, N = 10).