Question 134451
Let {{{w}}}mi/hr = speed walking
Then {{{w + 6}}} = speed running
His total time for running and walking
was 45 min or 3/4 hr
He ran 5 mi
He walked 1 mi
In words:
(distance he ran/speed running) + (distance he walked/speed walking) = 
(total time)
{{{5 / (w + 6) + 1 / w = 3/4}}}
multiply both sides by {{{w*(w + 6)}}}
{{{5w + w + 6 = (3/4)*w*(w + 6)}}}
Multiply both sides by 4
{{{24w + 24 = 3*(w^2 + 6w)}}}
Divide both sides by 3
{{{8w + 8 = w^2 + 6w}}}
{{{w^2 - 2w - 8 = 0}}}
{{{(w - 4)(w + 2) = 0}}}
{{{w = 4}}}
{{{w = -2}}} This answer makes no sense in this problem
{{{w + 6}}} = speed running
{{{4 + 6 = 10}}}
His speed running was 10 mi/hr
check answer:
{{{5 / (w + 6) + 1 / w = 3/4}}}
{{{5 / (4 + 6) + 1 / 4 = 3/4}}}
{{{5/10 + 1/4 = 3/4}}}
{{{2/4 + 1/4 = 3/4}}}
OK