You need to remove = in this line <%= @project.tasks.each do |task| %>
<% @project.tasks.each do |task| %>
-
<%= check_box_tag "task_done_#{task.id}", "", task.done %>
<%# <%= link_to task.title, task %>
<%= task.title %>
<% end %>
Small Note:
<% %> - Executes the code.
<%= %> - Prints the Output.
