We have looked at how to solve equations with one unknown value, but what happens when there are two unknown values? An equation with two unknown values will have infinitely many solutions.

then you can compare the two services using simultaneous equations. Based on the answer you get, you’ll know to use Service A for any packages smaller than that, and Service B for any packages ...

In this case the efficiency of the estimation may be improved by taking these cross-equation correlations into account. Seemingly unrelated regression (SUR), also called joint generalized least ...