Incorrect. Find the intensity of noise for a library and for traffic:
$\displaystyle{40}={10}{\log{{\left(\frac{{l}}{{P}_{{0}}}\right)}}}\usepackage{cmbright}\Huge\$ and $\displaystyle{85}={10}{\log{{\left(\frac{{t}}{{P}_{{0}}}\right)}}}\usepackage{cmbright}\Huge\$

Divide both equations by 10, rewrite as exponential equations, and multiply both sides by $\displaystyle{P}_{{0}}\usepackage{cmbright}\Huge\$ . Divide t by l to compare the two noise levels. Use the laws of exponents to simplify the quotient and evaluate, using a calculator.