title: Multiply columns in dataframe by values given in another dataframe
body: <p>I've been trying to accomplish this in dplyr but not been able to figure it out.</p>
  <p>In one data frame (df1) I have columns with values.</p>
  <pre><code>|A  |B  |
  |23 |43 |
  |24 |11 |
  </code></pre>
  <p>In another data frame (df2) I have valus.</p>
  <pre><code>|Column|Value|
  |A     |0.12 |
  |B     |1.23 |
  </code></pre>
  <p>I want to somehow multiple every cell in column 'A' of df1 by the given value in df2 for that column. Seems like it should be trivial but I've not quite figured out the correct syntax. I suspect I was use mutate, but any advice would be appreciated.</p>
  <p>Mostly trying to accomplish this in dplyr but welcome to other suggestions.</p>