First, we set up the equation 3x=120, dividing both sides by three to find that x=40
Then we multiply X by 2 to find that 40*2= <<40*2=80>>80
As 80/2=40, and 40+80=<<120=120>>120, we find the sizes of the two piles as the larger pile is twice as big as the smaller pile, confirming that 80 is the answer.
#### 80