SAT Question 022e9894: Percentages answer and explanation with Desmos solution

It's given that $1,250$ people attended the first information session, and that $72\%$ of the people who attended the first information session attended the second information session. Therefore, the number of people who attended the first and second information sessions can be found by calculating $72\%$ of $1,250$, which is equal to $1,250\left(\frac{72}{100}\right)$, or $900$. It's also given that $36\%$ of the people who attended the first and second information sessions attended the third information session. Since $900$ people attended the first and second information sessions, the number of people who attended the first, second, and third information sessions can be found by calculating $36\%$ of $900$, which is equal to $900\left(\frac{36}{100}\right)$, or $324$. Therefore, $324$ people attended all three information sessions.