<PRE><B>Question 478086</B>
Let {{{x}}}= The miles she ran on Monday
given:
On Wednesday, she ran 
{{{ x - 3 }}}
On Friday she ran
{{{ 2*(x - 3) }}}
and
{{{ x + x - 3 + 2*(x - 3)  = 21 }}}
{{{ 2x - 3 + 2x - 6 = 21 }}}
{{{ 4x - 9 = 21 }}}
{{{ 4x = 30 }}}
{{{ x = 7.5 }}}
On wed: 
{{{ x - 3 = 4.5 }}}
On fri:
{{{ 2*(x-3) = 2*(7.5 - 3) }}}
{{{ 2*4.5 = 9}}}
She ran 7.5 mi on Mon,
4.5 mi on Wed
9 mi on fri</PRE>