lass="op">/</span> <span class="op">(</span><span class="va">air_time</span> <span class="op">/</span> <span class="fl">60</span><span class="op">)</span></span>
<span><span class="op">)</span></span></code></pre></div>
<p>Instead, use:</p>
<div class="sourceCode" id="cb10"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="fu"><a href="../reference/mutate.html">mutate_dt</a></span><span class="op">(</span><span class="va">flights</span>,gain <span class="op">=</span> <span cla