SAT Question cc3e9528: Linear Equations In Two Variables answer and explanation with Desmos solution

When the graph of an equation in the form $Ax+By=C$, where $A$, $B$, and $C$ are constants, is translated down $k$ units in the xy-plane, the resulting graph can be represented by the equation $Ax+B\left(y+k\right)=C$. It's given that the graph of $9x-10y=19$ is translated down $4$ units in the xy-plane. Therefore, the resulting graph can be represented by the equation $9x-10\left(y+4\right)=19$, or $9x-10y-40=19$. Adding $40$ to both sides of this equation yields $9x-10y=59$. The x-coordinate of the x-intercept of the graph of an equation in the xy-plane is the value of $x$ in the equation when $y=0$. Substituting $0$ for $y$ in the equation $9x-10y=59$ yields $9x-10\left(0\right)=59$, or $9x=59$. Dividing both sides of this equation by $9$ yields $x=\frac{59}{9}$. Therefore, the x-coordinate of the x-intercept of the resulting graph is $\frac{59}{9}$. Note that 59/9, 6.555, and 6.556 are examples of ways to enter a correct answer.