Definite Integration

If $\phi(x)=\frac{1}{\sqrt{x}} \int\limits_{\frac{\pi}{4}}^x\left(4 \sqrt{2} \sin t-3 \phi^{\prime}(t)\right) d t, x>0$,


then $\emptyset^{\prime}\left(\frac{\pi}{4}\right)$ is equal to :