title: composer install - Your requirements could not be resolved to an installable set of packages
body: <p>I have an error when I want to run the <code>composer install</code> on my project.
  errors issued like this:</p>
  
  <pre><code>arief@arief-X45C:~/Triplogic/tripologic-admin-laravel$ sudo composer install
  Loading composer repositories with package information
  Installing dependencies (including require-dev) from lock file
  Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - Installation request for symfony/event-dispatcher v4.0.1 -&gt; satisfiable by symfony/event-dispatcher[v4.0.1].
      - symfony/event-dispatcher v4.0.1 requires php ^7.1.3 -&gt; your PHP version (7.0.22) does not satisfy that requirement.
    Problem 2
      - Installation request for doctrine/instantiator 1.1.0 -&gt; satisfiable by doctrine/instantiator[1.1.0].
      - doctrine/instantiator 1.1.0 requires php ^7.1 -&gt; your PHP version (7.0.22) does not satisfy that requirement.
    Problem 3
      - Installation request for symfony/yaml v4.0.1 -&gt; satisfiable by symfony/yaml[v4.0.1].
      - symfony/yaml v4.0.1 requires php ^7.1.3 -&gt; your PHP version (7.0.22) does not satisfy that requirement.
    Problem 4
      - symfony/event-dispatcher v4.0.1 requires php ^7.1.3 -&gt; your PHP version (7.0.22) does not satisfy that requirement.
      - symfony/http-kernel v3.4.1 requires symfony/event-dispatcher ~2.8|~3.0|~4.0 -&gt; satisfiable by symfony/event-dispatcher[v4.0.1].
      - Installation request for symfony/http-kernel v3.4.1 -&gt; satisfiable by symfony/http-kernel[v3.4.1].
  </code></pre>
  
  <p>and i have my <code>composer.json</code> file like this:</p>
  
  <pre><code>{
      "name": "laravel/laravel",
      "description": "The Laravel Framework.",
      "keywords": ["framework", "laravel"],
      "license": "MIT",
      "type": "project",
      "require": {
          "php": "&gt;=5.6.4",
          "brozot/laravel-fcm": "^1.2",
          "guzzlehttp/guzzle": "^6.3",
          "laravel/framework": "5.4.*",
          "laravel/tinker": "~1.0",
          "maatwebsite/excel": "^2.1",
          "prettus/l5-repository": "^2.6",
          "pusher/pusher-php-server": "^3.0",
          "yajra/laravel-datatables-oracle": "8.*",
          "zizaco/entrust": "5.2.x-dev"
      },
      "require-dev": {
          "fzaninotto/faker": "~1.4",
          "mockery/mockery": "0.9.*",
          "phpunit/phpunit": "~5.7"
      },
      "autoload": {
          "classmap": [
              "database"
          ],
          "psr-4": {
              "App\\": "app/"
          },
          "files": [
              "app/Helper/HelperFunction.php"
          ]
      },
      "autoload-dev": {
          "psr-4": {
              "Tests\\": "tests/"
          }
      },
      "scripts": {
          "post-root-package-install": [
              "php -r \"file_exists('.env') || copy('.env.example', '.env');\""
          ],
          "post-create-project-cmd": [
              "php artisan key:generate"
          ],
          "post-install-cmd": [
              "Illuminate\\Foundation\\ComposerScripts::postInstall",
              "php artisan optimize"
          ],
          "post-update-cmd": [
              "Illuminate\\Foundation\\ComposerScripts::postUpdate",
              "php artisan optimize"
          ]
      },
      "config": {
          "preferred-install": "dist",
          "sort-packages": true,
          "optimize-autoloader": true
      }
  }
  </code></pre>
  
  <p>anyone who can help me, it will be very helpful.</p>