title: How to compare two analytical equations for missing elements in Mathematica
body: <p>I have two equations:</p>
  
  <pre><code>(1) Eq1 = -((A N1 P (A B k (a N1 + aa P - r) + (d + A B r) R))/k)
  </code></pre>
  
  <p>(2) <code>Eq2 = R*N1*P,</code> where </p>
  
  <pre><code>R = (k (aa B m - a mm + A B r))/d;
  P = (-a^2 b k mm - A B m r + a k (aa bb m + A b B r))/(A d);
  N1 = (-aa^2 bb k m + A mm r + aa k (a b mm - A bb r))/(A d);
  </code></pre>
  
  <p>I want to compare (Eq2) to (Eq1) to find the missing elements. Is there an easy way to do that in mathematica?</p>
  
  <p>The answer is Eq1 = <code>-((A N1 P (A B k (a N1 + aa P - r) + (d + A B r) R))/k)</code> is equal to <code>- A R P N1 d/k</code> (i.e. Eq2 needs to be multiplied be (<code>-Ad/k</code>)</p>
  
  <p>I tried doing <code>FullSimplify[Eq1/Eq2]</code> which is <code>-((A (-a d mm + A^2 B^2 r^2 + aa B (d m + a A (b B - bb) k r)))/(k (aa B m - a mm + A B r)))</code> that doesn't help me so much. </p>