Velocity because it gives the displacement and time
I'm pretty sure the answer is gold
Let the unknown distance be xmiles
x/39-x/72=11hr
72x-39x/2808=11hr
33x/2808=11
33x= 30888
x=936miles
U can substitue back to check
at speed of 72mph, he would need 936/72=13hrs
at speed of 39mph, he would need 936/39=24hr
the difference is 24-13=11
The inert gases do not ordinarily for compound. the halogens are extremely reactive whereas the inert gases tends to be unreactive....hope helps