SAT Question f14484a5: Linear Equations In One Variable answer and explanation with Desmos solution

Choice D is correct. It's given that during a certain day, the number of $9$ -inch frying pans the manufacturing plant makes is $n$ and the number of $7$ -inch frying pans it makes is $10$. It's also given that during this day the number of $10$ -inch frying pans that the manufacturing plant makes is $4$ times the number of $9$ -inch frying pans, or $4n$. Therefore, the total number of $7$ -inch, $9$ -inch, and $10$ -inch frying pans the manufacturing plant makes is $n+10+4n$, or $5n+10$. It's given that during this day the manufacturing plant makes $100$ frying pans total. Thus, the equation $5n+10=100$ represents this situation.