Question 157597
for the level road,
{{{t = 3}}}hrs
Let average speed = {{{s + 20}}}
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For the winding road,
{{{t = 4}}}hrs
Let average speed = {{{s}}}
{{{3*(s + 20) + 4s = 305}}}
{{{3s + 60 + 4s = 305}}}
{{{7s = 245}}}
{{{s = 35}}}
{{{s + 20 = 55}}}mi/hr
The average speed on the level road is 55 mi/hr