i have a laney tf412a cab that im selling privately

the buyer has a laney lx120 head which puts out at 4 0hms

my cab has two jack sockets at the back, and nearby writing suggests that one is 4 ohm and the other is 8ohm

will this head work with my cab?
i want to know both for the sake of the sale and for my own knowledge ( how this whole ohms impendance thing works in general)
help wanted!