During the 1950’s, QST ran a regular feature called Quist Quiz, which presented an electronic brain teaser. This one appeared in the May 1959 issue.

I’ll provide the solution tomorrow.  If you can’t wait, you can look in the June 1959 issue, where the answer (but not the full solution) is shown.

Unless you want to do a lot of trial and error, you’ll probably need to use the quadratic formula,  Back in the day, the 1959 ham probably had to go dig out his old algebra textbook.  Today, you can just click on the link and Wikipedia will help you.