Question 1204324
Every day, Jane and Bill both drive to a parking lot, and then take a subway to get to work. 

Jane drives {{{25km}}} at {{{60( km/h)}}}, and then takes a northbound subway that averages {{{35 (km/h)}}} for {{{18km}}} 

while Bill drives {{{40km}}} at {{{80( km/h)}}} and then takes a southbound subway that averages {{{24 (km/h)}}} for {{{25km}}}. 

It takes each of them {{{15min}}} to change from car to subway, and they arrive at the same destination at {{{8:30a.m}}}. 

At what time does the earliest of them leave home?



Janes time:
{{{ t[1] = (25/60)h }}}
{{{ t[1] = (5/12)h }}}

 takes a northbound subway that averages 
{{{ t[2] = (18/35)h }}}


Bill's time:
{{{ t[1] = (40/80)h }}}
{{{ t[1] = (1/2)h }}}
 takes a southbound subway that averages
{{{ t[2] = (25/24)h }}}


Add {{{15min= (15/60)h = (1/4)h }}} to each one's time


Jane's time:

{{{ 5/12 + 18/35 + 1/4 = 124/105=1.18}}}=>{{{1h}}}{{{10}}}’

{{{8h}}}{{{30}}}'
-
{{{1h }}}{{{10}}}’
---------------------------------
{{{7h}}}{{{20}}}’


Bill's time:

{{{1/2 + 25/24 +1/4 = 43/24=1.79h }}}=>{{{1h }}}{{{47}}}’ to the nearest minute


{{{8h}}}{{{30}}}'
-
{{{1h }}}{{{47}}}’
---------------------------------
{{{6h }}}{{{42}}}’



Answers:
Jane ={{{ 7:20AM}}}
Bill = {{{6:42AM}}}