Andy left his home at 6.30 a.m.<br>He walked leisurely to his school at a speed of 40 $$m/min$$.<br>His father discovered that Andy had forgotten to bring his thermometer and rushed out of the house at 6.36 a.m.<br>He finally caught up with Andy at 6.46 a.m. <hr> What was his father's average speed? <br> <input min="0" type="number" id ="imp6pg167q6b_1" class="lineinput" placeholder="?" /> $$m/min$$