Can two unknowns of two *unrelated* linear equations be determined?

If I'm understanding the scenario correctly, wouldn't it just be: $$ \begin{cases} r + s = 2 \;\mathrm{million} \\ 6r + 15s = 15 \;\mathrm{million} \end{cases} $$

To take the roughness of the equations into account, we can edit our constants to incorporate an error term: $$ \begin{cases} r + s = (2 \;\mathrm{million} \pm e_c) \\ 6r + 15s = (15 \;\mathrm{million} \pm e_r) \end{cases} $$ where $e_c$ is the "error in the count" and $e_r$ is the "error in the revenue." We can just solve these normally for $r$ and $s$ and see what happens to the error terms. Scratching it out, I get something like: $$ \begin{align} s = \frac{1}{3} \;\mathrm{million} \mp \frac{2}{3}e_c \pm \frac{1}{9}e_r \\ r = \frac{5}{3} \;\mathrm{million} \pm \frac{5}{3}e_c \mp \frac{1}{9}e_r \end{align} $$ This quantifies how much the error in the original equations propagates through to the values for $s$ and $r$. We see that any error in the estimation for the total count has much more influence over the values of $r$ and $s$ than errors in the revenue.