<PRE><B>Question 612723</B>
t = d / r ___ the total time is 2 hr


2 = (49 / x) + [4 / (x - 5)]


the common denominator is the product of the two denominators
___ change the denominator of  a fraction by multiplying by the missing factor, divided by itself; eg. [(x - 5) / (x - 5)]
___ a quantity divided by itself equals one; multiplying by one does not change the value of the fraction


2 = (49 / x)[(x - 5) / (x - 5)] + [4 / (x - 5)](x / x)


2 = {[49(x - 5)] / [x(x - 5)]} + {[4(x)] / [x(x - 5)]}


2[x(x - 5)] = 49(x - 5) + 4(x)


2x^2 - 10x = 53x - 245 ___ 2x^2 - 63x + 245 = 0


use the quadratic formula to find x</PRE>