There were d passengers in the train. 15% of all of them went in the first car, 20% went in the second car. how many passengers were in the rest of the train?

13/20d

Step-by-step explanation:

There are a total of "d" people in the train so if you wanted to find out how many were left you would minus 35% of d from d. This is because the first two parts together had 35% of the people and then you would minus that from d to find out about the rest of the train.

d-35%(d)

=13/20d