SAT Question 8bb94668: Percentages answer and explanation with Desmos solution

Choice D is correct. It’s given that the speeds of objects A, B, and C are $a$ meters per second, $b$ meters per second, and $c$ meters per second, respectively. If the speed of object A is $5,900\%$ of the speed of object C, this means that $a=\frac{5,900}{100}c$, or $a=59c$. If the speed of object C is $0.008\%$ of the speed of object B, this means that $c=\frac{0.008}{100}b$, or $c=0.00008b$. Dividing both sides of this equation by $0.00008$ yields $\frac{1}{0.00008}c=b$, or $12,500c=b$. Since $a=59c$ and $b=12,500c$, it follows that $a+b=59c+12,500c$, or $a+b=12,559c$. Therefore, the expression $12,559c$ represents the value of $a+b$ in terms of $c$.