Why did Russia, Prussia, and Austria agree to partition Poland?

In 1730 the neighbors of the Polish–Lithuanian Commonwealth (Rzeczpospolita), namely Prussia, Austria and Russia, signed a secret agreement to maintain the status quo: specifically, to ensure that the Commonwealth laws would not change.

So basically they did it to ensure that the commonwealth laws would not change.

how do you know that

explanation:

the branch of biology that deals with the normal functions of living organisms and their parts.

the way in which a living organism or bodily part functions.