Is it

I would go one step at a time. If y=f(x) then

f(3x) is f(x) compressed by a factor of 3 (in other words you'll complete 3 cycles in every 2pi radians)

f(x-pi) is f(x) shifted pi units to the right on the x axis

(3/4)f(x) is a vertical "stretch" of 3/4. For trig graphs this only really changes the extrema - in this case f(x) will vary between -3/4 and 3/4

-f(x) is f(x) inverted/flipped in the x axis

4-f(x) is f(x) shifted up the y axis by 4 units.

If you confirm the equation in question I will graph these steps for you using software