Question: Tally quiz average so far in random question bank?

Hey Community!

I've run into a wall, and I've spent hours searching the ELH forums for an answer that works, to no avail.

I have a set of randomized quiz slides drawn from a bank, and I've already got variables and triggers to give me the final % total, the count of possible correct answers so far, and tally of questions answered correctly so far. BUT, I can't figure out how to just calculate the the learner's score % as they progress: So when they get to slide E, having correctly answered 12 out of 14 possible so far, then they should see that they currently are at 86% before they move on to slide F. 

This sounds so easy, but my brain is aching, and I bet one of you bright folks can tell me a simple way to make this happen on random bank questions.

Thanks!