Let's begin by identifying key information given to us:
Exponential growth and decay functions are written in standard form (as shown below):
[tex]\begin{gathered} F\mleft(t\mright)=A_g\cdot bkt \\ where\colon \\ A_g=initial\text{ }amount \\ b=growth\text{ }factor \\ k=growth\text{ }rate \\ t=time \end{gathered}[/tex]Both exponential and decay functions are time-dependent functions.
As such, the ''t'' in the formula represent ''time''