HS.F-BF.A.1  Write a function that describes a relationship between two quantities.

HS.F-BF.A.1.a  Determine an explicit expression, a recursive process, or steps for calculation from a context.

HS.F-BF.A.1.b  Combine standard function types using arithmetic operations. For example, build a function that models the temperature of a cooling body by adding a constant function to a decaying exponential, and relate these functions to the model.