SAT Question 2875ba81: Systems of Linear Equations answer and explanation with Desmos solution

Choice A is correct. The given system of linear equations can be solved by the elimination method. Multiplying each side of the second equation in the given system by $3$ yields $\left(2x+2y\right)(3)=\left(10\right)\left(3\right)$, or $6x+6y=30$. Subtracting this equation from the first equation in the given system yields $\left(6x+7y\right)-\left(6x+6y\right)=\left(28\right)-\left(30\right)$, which is equivalent to $\left(6x-6x\right)+\left(7y-6y\right)=28-30$, or $y=-2$.