What is the maximum amount of a paycheck that can be garnished for child support?

My fiance has 5 kids with 3 mothers. I am the second mother. He and I dated about 14 years ago, I got pregnant but we went our separate ways until about a year ago we rekindled the relationship again. During the last 12 years he was married and had 3 kids with baby mama # 3. Now we are going to court to finalize the divorce and now he will have to pay child support for those 3 kids. The first child he had with mom # 1 he is paying child support for and is almost caught up on the arrears from that kid. I have never gone after him for money all this time, I just raised my kid alone, but since we have one together he will get a credit against the others child support. My question is how much can ors in Utah take every check to pay the other 2 moms. Can they take his whole check?