title: Subtract and divide using one mutate_across function in dplyr
body: <p>I have a data set that looks like the iris data set.</p>
  <pre><code>  Sepal.Length Sepal.Width Petal.Length Petal.Width Species
  1          5.1         3.5          1.4         0.2  setosa
  2          4.9         3.0          1.4         0.2  setosa
  3          4.7         3.2          1.3         0.2  setosa
  4          4.6         3.1          1.5         0.2  setosa
  5          5.0         3.6          1.4         0.2  setosa
  6          5.4         3.9          1.7         0.4  setosa
  </code></pre>
  <p>I would like across Sepal.Length:Petal.Width to subtract each value with the number <strong>2</strong> and then divide the outcome by <strong>4</strong>. How can I do this in one line with mutate_across in dplyr instead of two?</p>
  <pre><code>iris %&gt;% 
    mutate(across(c(Sepal.Length:Petal.Width), ~. -2 )) %&gt;% 
    mutate(across(c(Sepal.Length:Petal.Width), ~. /4 )) 
  </code></pre>