Answer :
With the following rules that are applied here I would say that the highest number that could possibly be made would be 87212160, you get this by doing the following
(5!)*(3!)+(1)*(4!)*(7!) enjoy!
(5!)*(3!)+(1)*(4!)*(7!) enjoy!
With the way the question is worded it can be interpreted in many ways. My interpretation was that you had to place the numbers in the order to which the number is greatest. If you did this the answer would simply be 75,431.