Question 1072771
Amount of time between 9:00 and 10:30 is  {{{1&1/2}}} hours.

Doing part (a) only:
<pre>
CAR      SPEED         TIME           DISTANCE

A         70          {{{1&1/2+3&1/2}}}      d

B          r           {{{3&1/2}}}           d
</pre>


{{{70(1&1/2+3&1/2)=(3&1/2)*r}}}


-
{{{70*5=(7/2)r}}}

{{{r=70*5*(2/7)}}}

{{{r=10*5*2}}}

{{{highlight(r=100)}}}