Evaluate: \( \frac{n p}{n+p} \) when \( \mathrm{n}=9 \) and \( \mathrm{p}=15 \)

To evaluate the expression \( \frac{n p}{n+p} \) when \( n = 9 \) and \( p = 15 \), we first substitute these values into the expression. \[ \frac{n p}{n+p} = \frac{9 \times 15}{9 + 15} \] Now calculate \( 9 \times 15 \): \[ 9 \times 15 = 135 \] Next, calculate \( 9 + 15 \): \[ 9 + 15 = 24 \] Now substitute these results back into the expression: \[ \frac{135}{24} \] To simplify \( \frac{135}{24} \), we can divide both the numerator and denominator by their greatest common divisor, which is 3: \[ \frac{135 \div 3}{24 \div 3} = \frac{45}{8} \] Thus, the evaluated value of the expression \( \frac{n p}{n+p} \) when \( n = 9 \) and \( p = 15 \) is \[ \frac{45}{8} \quad \text{or approximately } 5.625. \]