SAT Question 8e2e424e: Percentages answer and explanation with Desmos solution

Choice C is correct. It's given that the number $k$ is $36\%$ greater than $50$. Therefore, the value of $k$ is the number $50$ plus $36\%$ of $50$. This can be rewritten as $k=50+\frac{36}{100}\times 50$. Multiplying the terms $\frac{36}{100}\times 50$ yields $18$, so $k=50+18$, or $k=68$. It's also given that $k$ is the product of $50$ and $r$, which can be rewritten as $k=50r$. Substituting $68$ for $k$ yields $68=50r$. Dividing both sides of this equation by $50$ yields $r=1.36$.