Two successive harmonic frequencies of a guitar string are 360 Hz and 420 Hz. What's the fundamental frequency

Could you please show me how to find it?

Thanks in advance!

420 - 360 = 60

Fundamental frequency is 60Hz

Every harmonic is a multiple of the fundamental, so if you've got two successive harmonics, then the difference between them is obviously the fundamental.

It's pretty simple. I'm not sure what else I can say to explain it... it's all right there.

harmonics are multiples of the fundamental frequency. Given that, they must be separated in frequency by that fundamental.

in this case, 420–360 = 60z, so that is the fundamental.
Fund: 60
harmonics, 120, 180, 240, 300, 360, 420, 480, etc.

Your second question around 280/350, if 280 and 350 are harmonics, then the fundamental is 350–280 = 70 Hz. Same answer, different method. either one works.

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