The class was divided into 3 + 2 = <<3+2=5>>5 parts.
So each part is equal to 100/5 = <<100/5=20>>20 students.
Since there are 3 parts for boys, then there are 20 x 3 = <<3*20=60>>60 boys in class.
So there are 100 - 60 = <<100-60=40>>40 girls in class.
Hence, there are 60 - 40 = <<60-40=20>>20 boys more than girls.
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