Question 904050
{{{336mi/r - 336/(r+6) = 1}}} |Multiplying thru by r(r+6) so as all denominators = 1
336(r+7) - 336r = r(r+6)
r^2 + 6r - 2352 = 0  (Tossing out the negative solution for unit measure)
 *[invoke quadratic "x", 1, 6,-2352]