SAT Question 483d208d: Linear Equations In Two Variables answer and explanation with Desmos solution

Choice D is correct. It's given that the equation $80S+90C=1,120$ represents this situation, where $S$ is the number of square tokens won, $C$ is the number of circle tokens won, and $1,120$ is the total number of points the tokens are worth. It follows that $80S$ represents the total number of points the square tokens are worth. Therefore, each square token is worth $80$ points. It also follows that $90C$ represents the total number of points the circle tokens are worth. Therefore, each circle token is worth $90$ points. Since a circle token is worth $90$ points and a square token is worth $80$ points, then a circle token is worth $90-80$, or $10$, more points than a square token.