Chemical Kinetics

Initial concentration of reactant in a first order reaction is $0.08 \mathrm{~mol} \mathrm{~dm}^{-3}$ What concentration would remain after 40 minute?

\(\left(\text { given } \frac{[\mathrm{A}]_0}{[\mathrm{~A}]_{\mathrm{t}}}=5.00\right)\)