title: Gurobi: Constraint formulation - Ratios decision variables
body: <p>Currently I am working with gurobipy and would like to model the following constraint (X1 to X4 are decision variables):</p>
  
  <pre><code>a * X1 = b * X2 = c * X3 = a * X4
  </code></pre>
  
  <p>Is there a simple way to do this?</p>