Yep, as the others said, it's what you are holding at full draw. For you that would be 16.5 lbs.

55 lbs x .70 = 38.5 lbs
55 lbs - 38.5 lbs= 16.5 lbs

I much prefer the math this way: 55lbs x .30 = 16.5

Anyhoo, hope this helped you.