I don't have a minor in math, and I instinctively thought "shrinking by 30x" means 1/30 of size.
It's nice because they're inverses - if you shrink by 30x, then grow by 30x, you're back where you started, whereas a 97% decrease in size followed by a 97% increase in size leaves you at ~6% of the original size.
If I had starting capital of 100 usd and it increased by 20x then that means I gained 2000 usd which is 20x of my starting capital.
EDIT: correction 30x is same as 3000%.