Question 989533
<pre>
WITH         r+w      t      2880
AGAINST      r-w      t      2400
</pre>


{{{system((r+w)t=2880,(r-w)t=2400)}}}


{{{system(rt+tw=2880,rt-tw=2400)}}}


Sum the corresponding members to eliminate the term tw.
{{{2rt=2880+2400}}}
{{{rt=(2880+2400)/2}}}
Not finished here yet, but,.... maybe you will?


BEST APPROACH IS HERE***********************************************
Note that there is also the two equivalent times.
{{{2880/(r+w)=2400/(r-w)}}}
and then
{{{2400(r+w)=2880(r-w)}}}


You were given r=330, so solve the last equation for w in terms of r, and then use the given r value to evaluate w.
OR, 
{{{2400/(330+w)=2400/(330-w)}}}
{{{5280w=480r}}}
{{{528w=48r}}}
{{{11w=r}}}
{{{w=r/11}}}
{{{w=330/11}}}
{{{highlight(w=30)}}}


Can you work with what is done and shown and solve?