SAT Question e9fb7774: Percentages answer and explanation with Desmos solution

Choice A is correct. Let $x$ represent the percentage of $300$ that is $75$. This can be written as $\frac{x}{100}\left(300\right)=75$, or $3x=75$. Dividing both sides of this equation by $3$ yields $x=25$. Therefore, $25\%$ of $300$ is $75$.