Help! I've got a system of equations that I solve and it has four sets of solutions, ie the output looks like: [[a= ,b= ,c= ,d=- ],[a= ,b= ,c= ,d= ],[a= ,b=- ,c= ,d= ],[a= ,b=- ,c= ,d=- ]] And specifically, I'm only interested in the solutions where both b and d are positive (the second solution in the list above). Is there a way to only solve for that solution or is there a way to extract out that solution? They're not always in the same order so I can't use something like: solve(...)[1] Thank you very much!