Question 417598
How far did Marie get in 1/4 hr?
{{{d[1] = 9*(1/4)}}}
{{{d[1] = 9/4}}} km
------------
The equation for Heather is:
{{{d[2] = 12*t[2]}}}
-------------
The equation for Marie is:
{{{d[2] - 9/4 = 9*t[2]}}}
-------------
Note that {{{d[2]}}} is the distance Heather has to go
to catch up with Marie
-------------
By substitution:
{{{12t[2] - 9/4 = 9t[2]}}}
{{{ 3t[2] = 9/4 }}}
{{{ t[2] = 3/4}}}
Note that {{{t[2]}}} is the time from 8:30 + 15 min to the time they meet
{{{1/4 + 3/4 = 1 }}} hr
Heather catches Marie 1 hr after 8:30, or 9:30