Question 1044595
{{{t}}}= time in minutes for Tom to walk to the center of the road
{{{b}}}= time in minutes for Bill to walk to the center of the road
Counting time in minutes starting at 4:00.
Tom left home at {{{-3t}}} (meaning {{{3t}}} minutes before 4:00)
Bill left home at {{{-3b}}} (meaning {{{3b}}} minutes before 4:00).
Tom arrived at Bill's at {{{-t}}} .
According to the problem that was {{{-3b+11}}} , so {{{-t=-3b+11}}}<-->{{{t=3b-11}}} .
Bill arrived at Tom's at {{{-b}}} .
According to the problem that was {{{-3t+15}}} , so {{{-b=-3t+15}}}<-->{{{b=3t-15}}} .
{{{system(t=3b-11,b=3t-15)}}}--->{{{system(t=3b-11,b=3(3b-11)-15)}}}--->{{{system(t=3b-11,b=9b-33-15)}}}--->{{{system(t=3b-11,b=9b-48)}}}--->{{{system(t=3b-11,b-9b=-48)}}}}--->{{{system(t=3b-11,-8b=-48)}}}--->{{{system(t=3b-11,b=(-48)/(-8))}}}--->{{{system(t=3b-11,b=6))}}}--->{{{system(t=3*6-11,b=6))}}}--->{{{system(t=7,b=6))}}}
So, Tom left {{{3t=3*7=21}}} minutes before 4:00, at {{{60-21=39}}} minutes after 3:00, meaning at {{{highlight("3:39")}}} , and
Bill left {{{3b=3*76=18}}} minutes before 4:00, at {{{60-18=42}}} minutes after 3:00, meaning at {{{highlight("3:42")}}} .