Nikka has 100 x 35/100 = <<100*35/100=35>>35 Chinese stamps.
She has 100 x 20/100 = <<100*20/100=20>>20 US stamps.
So, Nikka has 35 + 20 = <<35+20=55>>55 stamps that are not Japanese.
Thus, Nikka has 100 - 55 = <<100-55=45>>45 Japanese stamps.
#### 45