A car moving at 108 km h-1 finds another car in front it going

A car moving at $108 \mathrm{~km} \mathrm{~h}^{-1}$ finds another car in front it going in the same direction at $72 \mathrm{~km} \mathrm{~h}^{-1}$. The first car sounds a horn that has a dominant frequency of $800 \mathrm{~Hz}$. What will be the apparent frequency heard by the driver in the front car? Speed of sound in air $=330 \mathrm{~m} \mathrm{~s}^{-1}$.