Atotal of 8 classes, each with 20 students will go on the field trip. two chaperones are needed for each class. one bus will hold 25 people. write an expression

8 classes x 20 students per class = 160 students

8 classes x 2 chaperones per class = 16 chaperones

Total people on the buses . . . . . . . . . . 176 people

The expression for the number of buses needed is:

         Number of buses = 1 + (the greatest integer in 176/25)

That's because if there are any people left over after the
last full bus of 25, they will need one more bus.

Unfortunately for the school's budget, this group needs
7 full buses carrying 25 people in each, and one bus
carrying one single person in it.

A possible solution to the problem would be to find somebody
who is certified as a bus driver and willing to work two jobs
on the field trip, to act as one of the chaperones.  Then they
might get away with only 7 buses.

If this doesn't work, then they can just forget about the whole
idea of 25 on a bus.  Loading them to capacity doesn't help,
because it still leaves one person without a ride.  They might
as well just put one class and their chaperones on each of the
8 buses, and give each load a little bit of room to spread out.

If there's one student out of 160 who is sick or otherwise doesn't
show up on field-trip day, then they can squeeze everybody into
7 fully-loaded buses.  But since they had to reserve 8 buses and
drivers, they'll probably have to pay for the eighth one anyway.