The following formula can be used to determine the quantity of a halo necessary to achieve the concentration required in a protection system Isolate " C " (A) \( C=\frac{100 w s}{V+w s} \) (B) \( C=\frac{100 s}{V-w s} \) (C) \( C=\frac{100}{V s-w s} \) (D) \( C=\frac{100 w s}{100-\bar{C}} \)

To isolate "C" in equation (A), you can start by manipulating the formula. Multiply both sides by the denominator, yielding \( C(V + ws) = 100ws \). Then, simply divide both sides by \( V + ws \) to get \( C = \frac{100ws}{V + ws} \). Voila! You have solved for "C". Now, remember that choosing the right formula depends on the context. If you’re considering practical applications, equation (D) is handy for calculating concentration based on a desired level of protection, as it directly relates the concentration to the existing conditions minus the aimed concentration. Always keep an eye on your variables and constraints!