REmember that
the speed is equal to divide the distance by the time
so
speed=d/t
in this problem we have
speed=3.6x10^4 miles/hour
d=7.2x10^8 miles
substitute in the formula
[tex]3.6\cdot10^4=\frac{7.2\cdot10^8}{t}[/tex]solve for t
[tex]\begin{gathered} 3.6\cdot10^4=\frac{7.2\cdot10^8}{t} \\ t=\frac{7.2\cdot10^8}{3.6\cdot10^4} \\ t=2.0\cdot10^4\text{ hours} \end{gathered}[/tex]therefore
