Question 1157811
-------------
175 miles and has an average of a certain speed. If the average speed had been 4mph more, he could have traveled 189 miles in the same length of time. 
------------


<pre>
                    SPEED       TIME      DISTANCE

TRAVELED             r           x         175

NEW CONDITION      r+4           x         189


ALL IN VARIABLES
TRAVELED            r           x         D
NEW COND          r+k           x         N
</pre>
{{{D/r=N/(r+k)}}}

-

{{{r/D=(r+k)/N}}}

{{{rN=D(r+k)}}}

{{{Nr=Dr+Dk}}}

{{{Nr-Dr=Dk}}}

{{{r(N-D)=Dk}}}

{{{highlight(r=Dk/(N-D))}}}
Substitute your given values.