))
</script></div>
  </div>

  <div class="problem">
    <div class="marginpar">This
      <a href="http://www.wolframalpha.com/input/?i=Solve+x%2B2y%3D3+and+4x-y%2Bz%3D7+and+x%3Dt">link</a>
    will show you how to specify which variable is $t$ when using
    Wolfram Alpha.</div>
    Find all solutions to the linear system $\begin{cases}x+y+z&=3\\2x-y&=4\end{cases}$.  
Since there are more variables than equations, this
    suggests there is probably not just one solution, but perhaps
    infinitely many. 