How much can private and federal student loans garnish from your wages?

I haven't paid my student loans in a long time- I know it's bad. They want too much, I can't afford to pay all of them and still eat and pay my rent. I don't qualify for any consolations. Or forbearances. I have my federal loans, private loans with Navient and Wells Fargo. My question is, if they are garnish me, how much can they take? Is there a cap? Can all three garnish me, at the same time? How much will I be left with? And then once I'm in garnishment, is there any turning back? What is there to expect? Has anyone gone through this? My balances are so highly, (100k) I don't see myself ever getting out of this debt.

Nobody should ever go to debt to go to college especially since today a college degree does not mean anything anymore (except for STEM degrees but those are being devalued as well).