Question 496648
You can think of this as one of them traveling
at the sum of their speeds and the other one
standing still.
I'll say Wilbur is standing still and Jaidee is
moving at the sum of their speeds.
If {{{s}}} is Jaidee's speed alone, their sum is
{{{ s + s + 18 = 2s + 18}}}
Jaidee drove for 3 hrs when Wilbur wasn't driving,
so Jaidee's head start was {{{ d[1] = s*3 }}}
{{{ 193 }}} km is their distance apart after {{{ 3 + 1 = 4 }}} hrs
{{{ 193 = 3s + (2s + 18)*1 }}}
{{{ 193 = 3s + 2s + 18 }}}
{{{ 5s = 193 - 18 }}}
{{{ 5s = 175 }}}
{{{ s = 35 }}}
{{{ s + 18 = 53 }}}
Jaidee's speed is 35 km/hr
check:
The sum of their speeds is {{{ 53 + 35 = 88 }}} km/hr
{{{ 193 = 3*35 + 88 }}}
{{{ 193 = 105 + 88 }}}
{{{ 193 = 193 }}}
OK