Answer: Solution: (80× 6+50× 3) ÷ (80-50) = (480+150) ÷ 30,
=630÷30,
=2 1 (minutes).
(2 1+3)×50
=24×50,
= 1200 (m).
A: So Xiaoming's home is1200m away from school.
So the answer is: 1200.
Comments: On the basis of finding the surplus and deficiency distance according to time × speed, finding the scheduled time according to the difference between (surplus and deficiency) ÷ twice allocation = the number of participants allocated is the key to complete this question.