So five consecutive integers starting from m are m, m+1...m+4
So the average of these terms is:
(5m+10)/5
And the average of six of these terms is:
(6m+15)/6
So the difference of these averages is:
d=(5m+10)/5-(6m+15)/6
d=(6(5m+10)-5(6m+15))/30
d=(30m+60-30m-75)/30
d=-15/30
d=-1/2