Problem $2.$ Two equal point sources discharge TC bacteria to an estuary as shown in the figure below. Assume salinity concentration of $8ppt$ in the estuary. Note that $100\%$ seawater has a salinity of $35ppt.$

a$.$ Determine the required percent removal in order that $TC\frac{2000}{100}ml.$ Assume equal removals at both plants and neglect wastewater flows $($doesn$\text{'}$t contribute to overall flow in estuary$).$

b$.$ Confirm $($a$)$ by plotting $N$ vs $x$ for the range of $-3x3.$