There are 1000 x 30/100 = <<1000*30/100=300>>300 people who are married.
There are 1000 x 50/100 = <<1000*50/100=500>>500 people who are single.
So, there are a total of 300 + 500 = <<300+500=800>>800 that are either married or single.
This means, 1000 - 800 = <<1000-800=200>>200 are children.
Therefore, there are 300 - 200 = <<300-200=100>>100 more married people than children.
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