To solve this problem, we need to find the capacity of the train car. Here are the steps to do that:

1. We know that the train car is at 120% capacity and there are 102 passengers on board.

2. We can use a proportion to find the total capacity of the train car. Let x be the total capacity of the train car.

  * 120% = 120/100 = 1.2

  * 1.2x = 102

  * x = 102/1.2

  * x = 85

3. Therefore, the capacity of the train car is 85 passengers.

Sources:

- [Source 1](https://roboguru.ruangguru.com/question/sebuah-kereta-api-memiliki-gerbong-setiap-gerbong-mengangkut-penumpang-di-suatu-stasiun_QU-UGNIEL7Q): This source provides a similar problem and solution using proportions to find the total capacity of the train car.

- [Source 4](https://oratoretku.wordpress.com/2014/09/25/cara-mudah-membaca-tiket-kereta-api-indonesia/): This source provides a guide on how to read train tickets in Indonesia, which could be useful for understanding the information provided on the train car.