Hi, can someone suggest how to do this please?

I have a number of students that go on work placement each sememster. It's
competitive as to which workplace they are assigned, so we've told them that
they will have priority based on their results from the previous semester
(GPA).

They list the workplaces they'd like to go in order of preference and then I
try and work out who goes where and make it as equitable as possible. The
number of workplaces that take students changes regularly.

So if anyone could please suggest how I:
Rank them on GPA, assign them to the workplace & am able to alter the
workplace numbers without pulling out my hair, it'd be really appreciated.

Cheers!