on</a></span><span class="op">(</span><span class="st">"N_d = Y/W"</span><span class="op">)</span> <span class="op">|&gt;</span></span>
<span>  <span class="fu"><a href="../reference/add_equation.html">add_equation</a></span><span class="op">(</span><span class="st">"H_d = Yd_e - C_d + H_h[-1]"</span><span class="op">)</span> <span class="op">|&gt;</span></span>
<span>  <span class="fu"><a href="../reference/add_equation.html">add_equation</a></span><span class="op">(</span><span class="st">"Yd_e = Yd[-1]"<