Question 1183834
Let d = distance from home to school

===> 2d = total distance travelled to and from school

===> {{{(d/2)/5 = d/10}}} = time in the walking part of the trip

===>{{{(d/2)/8 = d/16}}} = time in the running part of the trip

===> {{{d/40}}} = time in the riding part, going back home.

===> Average speed to and from school = Total distance/Total time of travel

 = {{{(2d)/(d/10 + d/16 + d/40) = 2/(1/10 + 1/16 + 1/40)  = 32/3 }}} kph