Mr Lim drove his car at a speed of 90 $$km/h$$ for the first 2 hours.<br>Then, he drove his car for the rest of the journey at a speed of 75 $$km/h$$ and took another 4 hours to reach his destination. <hr> Find the car's average speed for the entire journey.<br> <input min="0" type="number" id ="imp6pg157q11_1" class="lineinput" placeholder="?" /> $$km/h$$