Couldn't find Photo without an IDについて

###前提・実現したい事
ruby on railsでコメント機能を実装して、コメント投稿ページを作成したいのですがエラーが出ます。

###発生している問題・エラーメッセージ

ActiveRecord::RecordNotFound (Couldn't find Photo without an ID):
  
app/controllers/answers_controller.rb:5:in `new'

###該当のソースコード
answers_controller.rb

rails
1class AnswersController < ApplicationController
2  
3  def new
4    @answer =Answer.new
5    @photo = Photo.find(params[:photo_id])
6  end
7 
8 
9  def create
10     @answer = current_user.answers.new(answer_params)
11    if @answer.save
12      redirect_back(fallback_location: root_path)
13    else
14      redirect_back(fallback_location: root_path)  
15    end
16  end
17  
18  private
19  
20  def answer_params
21    params.require(:answer).permit(:content, :photo_id)
22  end
23end
24

answers/new.html.erb

rails
1<%= image_tag @photo.image.url if @photo.image? %>
2

photo.rb

rails
1class Photo < ApplicationRecord
2  mount_uploader :image, ImageUploader
3  
4  validates :user_id, presence: true
5  validates :content, presence: true
6  validates :image, presence: true
7  
8  belongs_to :user
9  has_many :answers, dependent: :destroy
10  
11end
12

answer.rb

rails
1class Answer < ApplicationRecord
2  belongs_to :user
3  belongs_to :photo
4end
5

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 :photos do
12    resources :answers, only: [:create, :new]
13  end
14  resources :users, only: [:index, :show, :create]
15  resources :photos
16  resources :answers, only: [:create, :new]
17end
18