Prepopulate a form field

What's the right syntax?

I've used all of these, none of them work.

&employe[first_87]={employe[first_27]}&employe[last_87]={employe[last_27]}

&employe[first_87]=employe[first_27]

&employe[last_87]={employe[last_27]}

&first_87={first_27}&last_87={last_27}

Hi vServices,

Thanks for reaching out to Jotform Support. Could you send us a link to the form you're working on and tell us what field you're trying to pre-populate? Any other specific details you can give us about what you're trying to do would be helpful as well.

Once we hear back from you we can move forward with a solution.