SAT Question 4e400635: Systems of Linear Equations answer and explanation with Desmos solution

Subtracting the second equation from the first equation in the given system of equations yields $\left(3x-3x\right)+\left(6-4\right)=4y-2y$, which is equivalent to $0+2=2y$, or $2=2y$. Dividing each side of this equation by $2$ yields $1=y$.