3.8 Exercise 74

Determine the function described and then use it to answer the question.

A container holds 100 ml of a solution that is 25 ml acid. If $n$ ml of a solution that is 60% acid is added, the function $C \left(n\right) = \frac{25 + .6 n}{100 + n}$ gives the concentration, $C ,$ as a function of the number of ml added, $n .$ Express $n$ as a function of $C$ and determine the number of mL that need to be added to have a solution that is 50% acid.