$(1$ point$)$ Using the method of $u-$substitution,

${\displaystyle \underset{1}{\overset{5}{}}}(3x-7{)}^{4}dx={\displaystyle \underset{a}{\overset{b}{}}}f(u)du$

where

$u=$

$($enter a function of $x)$

$du=q,dx($enter a function of $x)$

$a=($enter a number$)$

$b=q,($enter a number$)$

$f(u)=($enter a function of $u).$

The value of the original integral is $$