What is the exponential decay rate (percent rate of change) of the equation below? \( f(x)=(.85)^{x} \) \( 85 \% \) \( 15 \% \) \( 25 \% \) \( 0.85 \% \)

1. The function is given by \( f(x) = (0.85)^x \). 2. In an exponential decay function of the form \( f(x) = a^x \), the base \( a \) represents the factor by which the function changes for each unit increase in \( x \). 3. Here, \( a = 0.85 \), which means the function retains \( 85\% \) of its value per unit increase in \( x \). 4. The decay rate is the percentage by which the function decreases each time step, calculated as: \[ \text{Decay Rate} = (1 - a) \times 100\% \] 5. Substituting \( a = 0.85 \) into the formula: \[ \text{Decay Rate} = (1 - 0.85) \times 100\% = 0.15 \times 100\% = 15\% \] 6. Therefore, the exponential decay rate of the equation \( f(x)=(0.85)^x \) is \( 15\% \).