<PRE><B>Question 953093</B>
w=distance walked; 6km-w=distance bused; t=time=distance/rate=30 min
{{{30 min=w/(5km/hr)+(6km-w)/(40km/hr)}}} Find common denominator and add.
{{{30 min=(8/8)(w/5km/hr)+(6km-w)/(40km/hr)}}}
{{{30 min=(8w+6km-w)/(40km/hr)}}} Multiply each side by 40km/hr.
{{{30min(40km/hr)=7w+6km}}} Convert to hrs and multiply. 
{{{30min(1hr/60min)(40km/hr)=7w+6km}}}
{{{20km=7w+6km}}} Subtract 6km from each side.
{{{14km=7w}}} Divide each side by 7.
{{{2km=w}}} ANSWER: Paul walks 2 kilometers.
CHECK:
{{{2km/(5km/hr)+(6km-2km)/(40km/hr)=30min}}}
{{{0.4hrs+4km/(40km/hr)=30 min}}}
{{{0.4hr+0.1hr=30 min}}}
{{{0.5hr(60min/hr)=30min}}}
30 min=30 min</PRE>