SAT Question 6feae9c3: Percentages answer and explanation with Desmos solution

Choice C is correct. It’s given that the total number of hours visitors used the exercise room increased from $t$ hours in July to $3.49t$ hours in August. It follows that the number of hours increased by $3.49t-t$, or $2.49t$. Let $p\%$ represent the percent increase in the exercise room use from July to August, or the percentage that $2.49t$ is of $t$. The value of $p$ can be found using the proportion $\frac{2.49t}{t}=\frac{p}{100}$, or $2.49=\frac{p}{100}$. Multiplying both sides of this equation by $100$ yields $p=249$. Therefore, the percent increase in the number of hours visitors used the exercise room from July to August is $249\%$.