SAT Question 8da536c6: Linear Equations In Two Variables answer and explanation with Desmos solution

Choice C is correct. It’s given that in $2010$, a swim club had a total of $35$ swimmers, each classified as either advanced or intermediate, and that $a$ represents the number of advanced swimmers in $2010$ and $b$ represents the number of intermediate swimmers in $2010$. It's also given that from $2010$ to $2020$, the number of advanced swimmers in the club increased by approximately $53\%$ and the number of intermediate swimmers in the club increased by approximately $44\%$. Thus, in $2020$, the approximate number of advanced swimmers in the club can be represented as $1.53a$ and the approximate number of intermediate swimmers in the club can be represented as $1.44b$. It's given that the total number of swimmers in the club increased by approximately $49\%$ from $2010$ to $2020$. Since the club had $35$ swimmers in $2010$, it follows that the total number of swimmers in $2020$ can be represented as $35(1.49)$. Since the sum of the number of advanced swimmers in $2020$ and the number of intermediate swimmers in $2020$ equals the total number of swimmers in $2020$, the equation $1.53a+1.44b=35(1.49)$ best represents this situation.