form_withでmodelの複数指定でのエラー

###前提・実現したい事。
投稿にコメント機能を実装しているのですが、form_withでモデルを複数指定するとエラーが出ます。

###発生している問題・エラーメッセージ

ActionView::Template::Error (undefined method `answer_photo_path' for #<#<Class:0x00007fa1981102b0>:0x00007fa1980b71d8>
Did you mean?  new_photo_path):

###該当のソースコード
routes.rb

rails
1Rails.application.routes.draw do
2  resources :photos
3  # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
4  root to: 'toppages#index'
5  
6  get 'login', to: 'sessions#new'
7  post 'login', to: 'sessions#create'
8  delete 'logout', to: 'sessions#destroy'
9  
10  get 'signup', to: 'users#new'
11  resources :users, only: [:index, :show, :create]
12  resources :photos
13  resources :answers, only: [:create]
14end
15

photos_controller.rb

rails
1class PhotosController < ApplicationController
2  before_action :set_photo, only: %i[ show edit update destroy ]
3
4  # GET /photos or /photos.json
5  def index
6    @photos = Photo.all
7  end
8
9  # GET /photos/1 or /photos/1.json
10  def show
11    @answer = Answer.new
12    @photo = Photo.find(params[:id])
13    @answers = @photo.answers
14  end
15
16  # GET /photos/new
17  def new
18    @photo = Photo.new
19  end
20
21  # GET /photos/1/edit
22  def edit
23  end
24
25  # POST /photos or /photos.json
26  def create
27    @photo = current_user.photos.new(photo_params)
28    
29    if @photo.save
30      flash[:success] = '投稿に成功しました。'
31      redirect_to photos_path
32    else
33      flash.now[:danger] = "投稿に失敗しました。"
34      render :new
35    end
36  end
37
38  # PATCH/PUT /photos/1 or /photos/1.json
39  def update
40    respond_to do |format|
41      if @photo.update(photo_params)
42        format.html { redirect_to @photo, notice: "Photo was successfully updated." }
43        format.json { render :show, status: :ok, location: @photo }
44      else
45        format.html { render :edit, status: :unprocessable_entity }
46        format.json { render json: @photo.errors, status: :unprocessable_entity }
47      end
48    end
49  end
50
51  # DELETE /photos/1 or /photos/1.json
52  def destroy
53    @photo.destroy
54    respond_to do |format|
55      format.html { redirect_to photos_url, notice: "Photo was successfully destroyed." }
56      format.json { head :no_content }
57    end
58  end
59
60  private
61    # Use callbacks to share common setup or constraints between actions.
62    def set_photo
63      @photo = Photo.find(params[:id])
64    end
65
66    # Only allow a list of trusted parameters through.
67    def photo_params
68      params.require(:photo).permit(:image, :content)
69    end
70end
71

answers_controller.rb

rails
1class AnswersController < ApplicationController
2  
3  def create
4    @photo = Photo.find(params[:photo_id])
5    @answer = @photo.answer.new(answer_params)
6    if @answer.save
7      redirect_to photo_path(@photo)
8    else 
9      flash.now[:alert] = 'コメント入力してください。'
10    end
11  end
12  
13  private
14  
15  def answer_params
16    params.require(:answer).permit(:content, :photo_id)
17  end
18end
19

photos/show.html.erb

rails
1<p id="notice"><%= notice %></p>
2<div class="row">
3  <div class="offset-md-3 col-md-5">
4    <p>
5  
6      <%= image_tag @photo.image.url if @photo.image? %>
7    </p>
8    
9    <p>
10      <strong>クイズの問題:</strong>
11      <%= @photo.content %>
12    </p>
13    <p>
14      <%= form_with(model:[@answer, @photo], method: :post) do |f| %>
15      <div class="form-group">
16          <%= f.text_area :content, class: 'form-control', rows: 5 %>
17      </div>
18        <%= f.submit 'Post', class: 'btn btn-primary btn-block' %>
19      <% end %>
20    </p>
21    </div>
22</div>
23
24<%= link_to '戻る', photos_path %> |
25<%= link_to '編集', edit_photo_path(@photo) %> 
26