SAT Question a71b1bc1: Systems of Linear Equations answer and explanation with Desmos solution

It's given that a piece of wire has a length of $32$ inches and is cut into two parts. It's also given that one part has a length of $x$ inches and the other part has a length of $y$ inches. It follows that the equation $x+y=32$ represents this situation. It's also given that the value of $x$ is $4$ more than $3$ times the value of $y$, or $x=3y+4$. Substituting $3y+4$ for $x$ in the equation $x+y=32$ yields $3y+4+y=32$. Combining like terms on the left-hand side of this equation yields $4y+4=32$. Subtracting $4$ from both sides of this equation yields $4y=28$. Dividing both sides of this equation by $4$ yields $y=7$. Substituting $7$ for $y$ in the equation $x=3y+4$ yields $x=3(7)+4$, or $x=25$. Therefore, the value of $x$ is $25$.