Задано прохождение светового луча после прохождения линзы. Построить прохождение луча до линзы, считая положение фокусов известным

1. Shop assistant: 'Are you being served by anyone?'
2. Hotel manager: 'I'm sorry. Pets aren't allowed here.'
3. Tour quide: The church was destroyed by a fire when it was being restored.'
4. Travel agent: 'The trip to Paris is highly recommended.'
5. Customer: 'Will transport from the airport to the hotel be arranged by you?'