report.html.erb

<%= form_tag(report_period_path, method: :get) do %>
  <%= date_field_tag :date_min %>
  <%= date_field_tag :date_max %>
  <%= submit_tag "期間指定", class: "btn btn-primary" %>
<% end %>
<div class="ads">
  <table class="table">
    <thead class="thead-dark">
      <tr>
        <th scope="col" class="h2">広告ID</th>
        <th scope="col" class="h2">Impression数</th>
        <th scope="col" class="h2">Click数</th>
        <th scope="col" class="h2">総費用(円)</th>
        <th scope="col" class="h2">CTR</th>
        <th scope="col" class="h2">CPM</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <% @reports.each do |report| %>
          <td class="h3 align-middle"><%= report.ad_id %></td>
          <td class="h3 align-middle"><%= report.imp %></td>
          <td class="h3 align-middle"><%= report.click %></td>
          <td class="h3 align-middle"><%= report.price %></td>
          <td class="h3 align-middle">
            <%= (report.click.to_f / report.imp.to_f).round(3) %></td>
          <td class="h3 align-middle">
            <%= (report.price / (1000 / report.imp)) %></td>
        </tr>
      <% end %>
    </tbody>
  </table>
</div>