Domain\Teacher\Teacher::matters PHP Method

    public function matters()
    {
        return $this->belongsToMany(Matter::class, 'teacher_matter');
    }

 /**
  * Associate matters.
  * @param  Teacher $teacher
  * @param  array     $matters
  */
 public function associateMatters(Teacher $teacher, array $matters)
 {
     $ids = [];
     foreach ($matters['matters'] as $matter) {
         $ids[] = $matter['id'];
     }
     $teacher->matters()->sync($ids);
 }