12 people are waiting at a subway stop to get on the train. however, the train only has space for 9 people to board. how many different combinations of people can get on the train?

What type of animal might be preserved in a tar pit

Feedback is given with little or no reservation 1.supportive 2.high-monitoring 3.positive 4.low-monitoring ?

17 a tourist was planning a trip by car for travelling at some constant speed for 2.5 hours. however, he found that if he increases the speed by 20 km/h he can cover the same distance in 30 minutes less time than it was planned. what was the planned speed of the tourist, in km/h?