Answer
$ \approx 59.8$ft
Work Step by Step
Given: $L=\dfrac{L_0}{2}$ and $k=18$
Now, we have $L=L_0e^{-kx}$ ...(1)
Then $\dfrac{L_0}{2}=L_0e^{-18x} \implies k=\dfrac{\ln (2)}{18} \approx 0.0385$
Now, when after another t = 14 hours, that is, $t=14+10 =24$
Then equation (1) becomes $\dfrac{L_0}{10}=L_0e^{-(0.0385)x}$
This implies that $\ln (10) =0.0385 x$
Hence, $x \approx 59.8$ft
