Hello, where exactly are you stuck? We can’t solve your problems for you, can only help ?What will be the equation like if I want to find y(f) from equation below ?
[imath]x(t)=\frac{2}{(\pi t)^2} \int y(f) \operatorname{Sin}^4(\pi f t) d f[/imath]
It could be possible that that t is a function of f (maybe t = f+4), so x(t) might be a function of f (even if you see no f's!)Sorry, I got stucked in the last line, since x(t) has no f variable