Let t be the time, in hours, elapsed till the buses are 791 miles apart, then we can set the following equation:
[tex]59mph\cdot t+54\text{mph}\cdot t=791\text{ miles.}[/tex]Solving the above equation for t we get:
[tex]\begin{gathered} 113\text{ mph}\cdot t=791miles, \\ t=\frac{791}{113}\text{hours,} \\ t=7\text{ hours.} \end{gathered}[/tex]Answer: 7 hours.