#routes
resources :listings do
  resources :orders, only: [:new, :create, :update, :show]
end

get 'thankyou' => "orders#thankyou"

#order controller
def thankyou
end

#thankyou.html
Thank you for your order - <br>
<%= @order.id %><br>
<%= @order.listing.name %><br>
<%= @order.price_sold %><br>