Julian's number of friends who are girls is .40*80 = <<.40*80=32>>32
Boyd has twice as many friends as Julian who are girls, a total of 2*32 = <<2*32=64>>64
If Boyd has 100 friends, he has 100-64 = <<100-64=36>>36 boys
The percentage of boys in Boyd's Facebook friends is 36/100*100 = <<36/100*100=36>>36
#### 36