The number of blue apples is 5, and if you receive twice as many yellow apples as the number of blue apples, there will be 5*2 = <<5*2=10>>10 yellow apples.
After receiving the yellow apples, you now have 10 yellow apples+5 blue apples = <<10+5=15>>15 apples.
When you give 1/5 of the total number of apples to the son, you part with 1/5*15 = <<1/5*15=3>>3 apples.
The total number of apples remaining is 15-3 = <<15-3=12>>12 apples.
#### 12