Martin invited 5 * 2 = <<5*2=10>>10 people from his school.
People from the sports club got 5 + 10 = <<5+10=15>>15 invitations.
So in total from the sports club, hometown and school, Martin invited 5 + 10 + 15 = <<5+10+15=30>>30 people.
All other invitations are 20% of the previous total, which means 20/100 * 30 = <<20/100*30=6>>6.
That means Martin invited to his party 30 + 6 = <<30+6=36>>36 people.
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