diff --git a/app/Http/Controllers/CountryController.php b/app/Http/Controllers/CountryController.php
index 2b9be507..df5e650f 100644
--- a/app/Http/Controllers/CountryController.php
+++ b/app/Http/Controllers/CountryController.php
@@ -9,8 +9,7 @@ class CountryController extends Controller
     public function index()
     {
         // TASK: load the relationship average of team size
-        $countries = Country::all();
-
+        $countries = Country::withAvg('teams', 'size')->get();
         return view('countries.index', compact('countries'));
     }
 }
diff --git a/app/Http/Controllers/ProjectController.php b/app/Http/Controllers/ProjectController.php
index e04fb1a6..92808802 100644
--- a/app/Http/Controllers/ProjectController.php
+++ b/app/Http/Controllers/ProjectController.php
@@ -2,7 +2,10 @@
 
 namespace App\Http\Controllers;
 
+use App\Models\Project;
+use App\Models\User;
 use Illuminate\Http\Request;
+use Illuminate\Support\Facades\DB;
 
 class ProjectController extends Controller
 {
@@ -10,6 +13,11 @@ public function store(Request $request)
     {
         // TASK: Add one sentence to save the project to the logged-in user
         //   by $request->project_id and with $request->start_date parameter
+        DB::table('project_user')->insert([
+            'project_id' => $request->project_id,
+            'start_date' => $request->start_date,
+            'user_id' => auth()->user()->id,
+        ]);
 
         return 'Success';
     }
diff --git a/app/Http/Controllers/UserController.php b/app/Http/Controllers/UserController.php
index 7ae1d3d6..1cf3cb89 100644
--- a/app/Http/Controllers/UserController.php
+++ b/app/Http/Controllers/UserController.php
@@ -3,12 +3,13 @@
 namespace App\Http\Controllers;
 
 use App\Models\User;
+use Illuminate\Database\Eloquent\Builder;
 
 class UserController extends Controller
 {
     public function index()
     {
-        $users = User::all();
+        $users = User::has('projects')->get();
 
         return view('users.index', compact('users'));
     }
diff --git a/app/Models/Attachment.php b/app/Models/Attachment.php
index 158b6470..d30d9a63 100644
--- a/app/Models/Attachment.php
+++ b/app/Models/Attachment.php
@@ -4,6 +4,7 @@
 
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\MorphTo;
 
 class Attachment extends Model
 {
@@ -11,8 +12,9 @@ class Attachment extends Model
 
     protected $fillable = ['filename', 'attachable_id', 'attachable_type'];
 
-    public function attachable()
+    public function attachable():MorphTo
     {
         // TASK: fill in the code to make it work
+        return $this->morphTo();
     }
 }
diff --git a/app/Models/Role.php b/app/Models/Role.php
index c2f3fc89..24099baa 100644
--- a/app/Models/Role.php
+++ b/app/Models/Role.php
@@ -14,6 +14,6 @@ class Role extends Model
     public function users()
     {
         // TASK: fix this by adding a parameter
-        return $this->belongsToMany(User::class);
+        return $this->belongsToMany(User::class, 'users_roles');
     }
 }
diff --git a/app/Models/Team.php b/app/Models/Team.php
index 13969525..a1744706 100644
--- a/app/Models/Team.php
+++ b/app/Models/Team.php
@@ -14,7 +14,7 @@ class Team extends Model
     public function users()
     {
         // TASK: fix this by adding some extra code
-        return $this->belongsToMany(User::class);
+        return $this->hasMany(User::class);
     }
 
 }
diff --git a/app/Models/User.php b/app/Models/User.php
index 3d7facd2..f792e3f4 100644
--- a/app/Models/User.php
+++ b/app/Models/User.php
@@ -45,12 +45,12 @@ class User extends Authenticatable
     public function tasks()
     {
         // TASK: fix this by adding a parameter
-        return $this->hasMany(Task::class);
+        return $this->hasOne(Task::class, 'users_id', 'id');
     }
 
     public function comments()
     {
-        // TASK: add the code here for two-level relationship
+        return $this->tasks->hasMany(Comment::class);
     }
 
     public function projects()
diff --git a/resources/views/tasks/index.blade.php b/resources/views/tasks/index.blade.php
index 8d229417..1c5602b7 100644
--- a/resources/views/tasks/index.blade.php
+++ b/resources/views/tasks/index.blade.php
@@ -1,5 +1,5 @@
 <ul>
     @foreach ($tasks as $task)
-        <li>{{ $task->name }} ({{ $task->user->name }})</li>
+        <li>{{ $task->name }} ({{ $task->user->name ?? '' }})</li>
     @endforeach
 </ul>