Write a function that describes a relationship between two quantities.
I.F.BF.1.a
Determine an explicit expression, a recursive process, or steps for calculation from a context.
I.F.LE.1
Distinguish between situations that can be modeled with linear functions and with exponential functions.
I.S.ID.6.a
Fit a function to the data; use functions fitted to data to solve problems in the context of the data. Use given functions or choose a function suggested by the context. Emphasize linear, quadratic, and exponential models.