Question 56235
Hi ac
During rush hour, Emily can drive 35 miles using the freeway in the same time that it takes to travel 30 miles on the side roads.  If Emily'e rate on the freeway is 10mi/h faster than her rate on the side roads, find her rate on the freeway.
The distance formula is:{{{highlight(d=rt)}}}
Solve the formula for t:
{{{d=rt}}}
{{{d/r=t}}}
Both the times are the same,so we we can set their d/r's = to each other.
On the side roads:
rate=r
distance=30
On the freeway:
rate=r+10
distance=35
Problem to solve:
{{{30/r=35/(r+10)}}}
{{{(r+10)*30/r=35(r+10)/(r+10)}}}
{{{(r+10)*30/r=35}}}
{{{r(r+10)*30/r=35r}}}
{{{(r+10)*30=35r}}}
{{{30r+300=35r}}}
{{{-30r+30r+300=35r-30r}}}
{{{300=5r}}}
{{{300/5=5r/5}}}
{{{60=r}}}
Rate on the sideroads:r=60 mph
Rate on the freeway:r+10=60+10=70 mph
Happy Calculating!!!