If 10 hens lay 80 eggs, then 1 hen lays 80 / 10 = <<80/10=8>>8 eggs in 10 days.
That means one hen is laying 8 / 2 = <<8/2=4>>4 eggs in 5 days.
So in 15 days, 1 hen will lay 3 times more eggs, so 4 * 3 = 12 eggs.
All hens in total will then lay 25 * 12 = <<25*12=300>>300 eggs in 15 days.
#### 300