LM567 understand math to get right frequency
Reading through the DATASHEET for the LM576, the formula is written on page 9. 

I assume what you want to know is the 'center frequency'. To do this, just follow the formula on the datasheet:


It is all there if you read through it. Alternatively, the link you provided to the instructible project even has a LINK to a page that will calculate the bandwidth and center frequency for you.

All the information you are requesting is there if you look for it.