<PRE><B>Question 384430</B>
  &lt;pre&gt;&lt;font size = 3 color = &quot;indigo&quot;&gt;&lt;b&gt;
Hi,         
Let x and (x+10)represent the speed hiking and biking respectively
D = r*t Or D/r = t. Total time for the trip was 5 hours.
Question States***
12/(x+10) + 8/x = 5hr Multiplying each term by x(x+10) so as all denominators = 1
 12x + 8(x+10) =5x(x+10)
Solving for x
  12x + 8x + 80 = 5x^2 + 50x
  5x^2 + 30x - 80 = 0
  5(x^2 + 6x - 16) = 0
(x + 8)(x - 2) = 0 Note:SUM of the inner product(8x) and the outer product(-2x) =6x
(x + 8= 0
  x = -8  Tossing out negative answer
(x - 2) = 0
  x = 2mph, speed hiking.  Speed biking was 12mph.   (2mph + 10mph)

CHECKING our Answer***
 12mi/12mph + 8mi/2mph = 1hr + 4hr = 5hr</PRE>