1. The problem asks to write an equation for the given graphs. 2. The description of the graphs indicates they are exponential decay curves starting near $y=9$ when $x$ is close to 0 and approaching $y=0$ as $x$ increases to 20. 3. The general form of an exponential decay function is: $$y = a e^{-bx}$$ where $a$ is the initial value (when $x=0$) and $b$ is a positive constant controlling the rate of decay. 4. Since the graphs start near $y=9$ at $x=0$, we have $a=9$. 5. So the equation for the top-right graph is: $$y = 9 e^{-bx}$$ where $b$ is some positive constant. 6. For the bottom-left graph, the function is given as $y = f(kx)$, which means the input $x$ is scaled by a factor $k$ inside the function $f$. 7. If $f(x) = 9 e^{-bx}$, then: $$y = f(kx) = 9 e^{-b(kx)} = 9 e^{-(bk)x}$$ This means the decay rate is scaled by $k$. 8. Without exact values for $b$ and $k$, the equations are: Top-right graph: $$y = 9 e^{-bx}$$ Bottom-left graph: $$y = 9 e^{-b k x}$$ where $b, k > 0$. This matches the description of the graphs. Final answer: Top-right graph: $y = 9 e^{-bx}$ Bottom-left graph: $y = 9 e^{-b k x}$