<% ads.each_with_index do |ad,i| %>
  <%= render :partial => "ads/ad", :locals => { :ad => ad } %>

  <% if [ 5, 10, 15 ].include? i %>
    <%= render partial: "partials/google_adsense", locals: { class_name: "desktop google_adsense_336_280", ad_slot: "7225596067"}  %>
    <%= render partial: "partials/google_adsense", locals: { class_name: "mobile google_adsense_320_100", ad_slot: "1977811266"}  %>
    <hr>
  <% end %>
<% end %>

<% ads.each_with_index do |ad,i| %>
  <%= render :partial => "ads/ad", :locals => { :ad => ad } %>

  <% if [ 5, 10, 15 ].include? i %>
    <div class="google_ad_wrapper">
      <%= render partial: "partials/google_adsense", locals: { class_name: "desktop google_adsense_336_280", ad_slot: "7225596067"}  %>
      <%= render partial: "partials/google_adsense", locals: { class_name: "mobile google_adsense_320_100", ad_slot: "1977811266"}  %>
    </div>
    <hr>
  <% end %>
<% end %>

Add a bit of space between ads and banners
Add a bit of space between ads and banners
