If frequencies are $$(\nu-1)$$ and $$(\nu+2)$$, then find the value of beats.

The equation of a progressive wave can be given by $$y=15\sin(660\pi t-0.02\pi x)$$ cm. The frequency of the wave is

A source of sound gives 5 beats per second, when sounded with another source of frequency 100 s$$^{-1}$$. The second harmonic of the source, together with a source of frequency 205 s$$^{-1}$$ gives 5 beats per second. What is frequency of the source?