To solve the equation
\[ \frac{1}{A} = \frac{1}{n} + \frac{1}{w} \]
for \(w\), we will first isolate \( \frac{1}{w} \).
- Rearrange the equation:
\[ \frac{1}{w} = \frac{1}{A} - \frac{1}{n} \]
- To combine the fractions on the right side, find a common denominator. The common denominator of \(A\) and \(n\) is \(An\):
\[ \frac{1}{w} = \frac{n}{An} - \frac{A}{An} \]
- Combine the fractions:
\[ \frac{1}{w} = \frac{n - A}{An} \]
- Now, take the reciprocal of both sides to solve for \(w\):
\[ w = \frac{An}{n - A} \]
Thus, the solution for \(w\) is:
\[ w = \frac{An}{n - A} \]