After Olivia gave William 10 napkins, he ends up with 15+10= <<10+15=25>>25 napkins.
Amelia gives William twice the number of napkins given to him by Amelia which is 2*10 = <<2*10=20>>20 napkins.
The total number of napkins William has now is 20+25 = <<20+25=45>>45 napkins.
#### 45