Answer: The answer is 2 buses and 4 vans.
Step-by-step explanation: Let 'b' be the number of buses and 'v' be the number of vans that will be needed.
The trip will use 6 drivers, and we need one driver for each vehicle, so number of drivers is equal to the number of vehicles used.i.e.,
Now, number of passengers in buses is 51b and number of passengers in vans is 10v. Since there are total 142 people, so
Substituting the value of 'v' from forst equation in the second equation, we have
Again, from the first equation, we get
Thus, there are 2 buses and 4 vans in the trip.