Question 1110002
Last part, is a little unclear.
  
Time quantity from 9:00 to 10:30 MIGHT be 1 and 1/2 hours.
<pre>
{{{r>70}}}

CAR           SPEED      TIME     DISTANCE(catch-up)
A              70        x+3.5      d
B              r          3.5       d
Difference                1.5
</pre>

x should be 1.5 hours.


<pre>
{{{r>70}}}

CAR           SPEED      TIME     DISTANCE(catch-up)
A              70          5        d
B              r          3.5       d
Difference                1.5
</pre>
You can find d.
{{{70*5=d}}}

{{{highlight(d=350)}}}

and you can then find r:
{{{350/3.5=r}}}
{{{highlight(r=100)}}}------speed for car B.