Question 847560
This is easier if you think of one of
them standing still and the other one
( either one ) moving at the sum of their speeds
Let Linda's speed = {{{ s }}}
Mary's speed  = {{{ s + 8 }}}
--------------------------
{{{ 324 = ( s + s + 8 )*3 }}}
{{{ 324 = 6s + 24 }}}
{{{ 6s = 300 }}}
{{{ s = 50 }}}
{{{ s + 8 = 58 }}}
Linda's speed is 50 mi/hr
Mary's speed is 58 mi/hr