## Precalculus (6th Edition) Blitzer

At $2000$ dollars in sales the earnings will be the same.
Let us assume that at $x$ dollar in sales, the earnings are the same. Now, the equations for the two cases become: 1: $\$200$and$5\%$commission on sales,$200+\frac{5x}{100}$2:$15\%$commission on sales,$\frac{15x}{100}$Then, for them to be the same we equate them:$\begin{align} & 200+\frac{5x}{100}=\frac{15x}{100} \\ & \frac{15x}{100}-\frac{5x}{100}=200 \\ & \frac{15x-5x}{100}=200 \\ & \frac{10x}{100}=200 \end{align}$And simplify it further:$\begin{align} & x=200\cdot \left( \frac{100}{10} \right) \\ & x=2000 \end{align}$Thus, the dollars of sales for which the earnings will be the same is$\$2000$.