Displaying an array result with rails

Here is my problem:

Everything works but I have a display that resembles ["1","2","3"]. I would like 1 2 3. I tried all to_ functions but that does not change ..

Thanks for your time.

model.rb:

validates :check, presence: true
validate :check_must_be_3

  private
    def checks_must_be_3
      if !check != 3
        errors[:base] << "You must select exactly 3 checks"
      end
    end

html:

<%= simple_form_for @answer do |f| %>
  <h3>Choose 3 answers</h3>
    <ul>
    <% (1..5).each do |x| %>
      <div class="checkbox">
        <label>
          <input type="checkbox" name="answer[check][]" id="optionsCheckbox<%= x %>" value="<%= x %>" />
          <%= x %>
        </label>
      </div>
    <% end %>
    <%= f.button :submit, "Submit", class: "btn btn-primary" %>
<% end %>

controller:

private

def answer_params
    params.require(:answer).permit(check:[])
end

answer is a string in db.