Question 774712
Send the two fastest guys first.
That first trip across would take {{{2}}} minutes.
Next, send one of them back with the flashlight. It does not matter which one.
The fast guy that goes back hands the flashlight over to the slow guys.
Next, the two slow guys cross together, using another {{{10}}} minutes of battery use.
After they cross, the slow guys hand the flashlight to the other fast guy at the other side.
That fast gut goes back to pick up his fast friend, and they cross together in {{{2}}} minutes.
The three trips in the right direction take {{{14}}} minutes:
{{{2+10+2=14}}}
The two trips back to bring the flashlight are done by the two fast guys and take a total of {{{3}}} minutes:
{{{2+1=3}}}
The total time crossing back and forth is
{{{14}}} minutes + {{{3}}} minutes = {{{17}}} minutes