已知\(A_{n}^{5}=56c_{n}^{7} \)，且\((1-2x)^{n}=a_{0}+a_{1}x+a_{2}x^{2}+a_{3}x^{3}+…+a_{n}x^{n}\)．
\((I)\)求\(n\)的值；
\((II)\)求\(a_{1}+a_{2}+a_{3}+…+a_{n}\)的值．
\((III)\)求\(\left|{a}_{1}\right|+\left|{a}_{2}\right|+\left|{a}_{3}\right|+…+\left|{a}_{n}\right| \)的值．