SAT Question f678483b: Nonlinear Functions answer and explanation with Desmos solution

It's given that the function $g\left(x\right)=-\frac{1}{55}\left(x+19\right)\left(x-35\right)$ gives the depth below the surface of the ocean, in meters, of the submersible device $x$ minutes after collecting a sample, where $x>0$. It follows that when the submersible device is at the surface of the ocean, the value of $g\left(x\right)$ is $0$. Substituting $0$ for $g\left(x\right)$ in the equation $g\left(x\right)=-\frac{1}{55}\left(x+19\right)\left(x-35\right)$ yields $0=-\frac{1}{55}\left(x+19\right)\left(x-35\right)$. Multiplying both sides of this equation by $-55$ yields $0=\left(x+19\right)\left(x-35\right)$. Since a product of two factors is equal to $0$ if and only if at least one of the factors is $0$, either $x+19=0$ or $x-35=0$. Subtracting $19$ from both sides of the equation $x+19=0$ yields $x=-19$. Adding $35$ to both sides of the equation $x-35=0$ yields $x=35$. Since $x>0$, $35$ minutes after collecting the sample the submersible device reached the surface of the ocean.