Correct. Find the intensity of noise for a library and for traffic:

$\displaystyle{40}={10}\cdot{\log{{\left(\frac{{l}}{{P}_{{0}}}\right)}}}\usepackage{cmbright}\Huge\$ and $\displaystyle{85}={10}\cdot{\log{{\left(\frac{{t}}{{P}_{{0}}}\right)}}}\usepackage{cmbright}\Huge\$

Divide both equations by 10: $\displaystyle{4}={\log{{\left(\frac{{l}}{{P}_{{0}}}\right)}}}\usepackage{cmbright}\Huge\$ and $\displaystyle{8.5}={\log{{\left(\frac{{t}}{{P}_{{0}}}\right)}}}\usepackage{cmbright}\Huge\$

Rewrite the equations as exponential equations: $\displaystyle{{10}}^{{4}}=\frac{{l}}{{P}_{{0}}}\usepackage{cmbright}\Huge\$ and $\displaystyle{{10}}^{{8.5}}=\frac{{t}}{{P}_{{0}}}\usepackage{cmbright}\Huge\$

Multiply both sides of the equations by $\displaystyle{P}_{{0}}\usepackage{cmbright}\Huge\$ : $\displaystyle{l}={{10}}^{{4}}{P}_{{0}}\usepackage{cmbright}\Huge\$ and $\displaystyle{t}={{10}}^{{8.5}}{P}_{{0}}\usepackage{cmbright}\Huge\$

Divide to compare the two noises: $\displaystyle\frac{{t}}{{l}}=\frac{{{{10}}^{{8.5}}{P}_{{0}}}}{{{{10}}^{{4}}{P}_{{0}}}}={{10}}^{{4.5}}\usepackage{cmbright}\Huge\$

Using a calculator, you will find that the noise of traffic is about 31,622.78 times as strong as the noise of a library.