Given:
Distance, d=756 miles.
Time taken, t=12 h.
The speed of Hans can be calculated as,
[tex]s=\frac{d}{t}=\frac{756}{12}=63\text{miles/h}[/tex]The new distance to be drived, D=504 miles.
Now, the time taken to travel distance D=504 miles with the same initial speed s is,
[tex]t=\frac{D}{s}=\frac{504}{63}=8\text{ h}[/tex]Therefore, Hans takes 8 hours to drive a distance of 504 miles.