Questions' number mapping with related files.

#1, #2. truck.html, assets/truck.css & assets/truck.js

#3. truck.php, src/Truck.php & src/TruckCopy.php

#4. group.php, src/GroupNumber.php

#5. productionTime.php, src/ProductionTime.php

#6. tableJoin.php, src/TableJoin.php & src/Database.php.

Please copy the .env.sample file to .env and fill the database configuration values (create database if not already existss) and execute tableJoinSchema.sql file to populate the database for #6 to work.