*6.2. Answer*

The fact that both *P* and *r* = *TR*/*TC* are on the left side of our Equations (4) and (5), respectively, in no way means that *P* = *r*. In the Figure 3 below, we illustrate how we arrived at our Equation (5), starting from our Equation (4). In our paper, we have not included for brevity ("after doing some mathematics") the auxiliary calculations presented in Figure 3 (in which, for simplicity, we have not used subscripts).

**Figure 3.** Description of the intermediate steps between Equations (4) and (5).

#### **7. Comments on the Use of a Single-Output Cost Function**
