Question 415215
Going downhill:
{{{d = (r + 1)*3}}}
Going uphill:
{{{d = r*6}}}
(I'm assuming the uphill and 
downhill trips are the same distance)
{{{(r + 1)*3 = 6r}}}
{{{3r + 3 = 6r}}}
{{{3r = 3}}}
{{{r = 1}}}
{{{r + 1 = 2}}}
Her speed downhill is 2 mi/hr
check answer:
{{{d = (r + 1)*3}}}
{{{d = 2*3}}}
{{{d = 6}}} mi
and
{{{d = r*6}}}
{{{d = 1*6}}}
{{{d = 6}}} mi
OK